Fifth Annual Turkey Awards: Prenatal Weight Restriction Extremism

Image from Wikimedia Commons

As we move forward into the new year, it's also time to look backwards at the old year and announce our Fifth Annual Turkey Awards.  Whoohooo!

The Turkey Awards are my opportunity to highlight bias or ignorance about "obesity" and pregnancy, insensitive treatment by a care provider towards a woman of size, or a trend in the care of women of size that is troubling and frustrating.

This year, the "winning" entry is an idiotic comment to a pregnant woman of size, as documented on My OB Said What!?! This comment represents both insensitive treatment of women of size and the deeper, more troubling trend of pressuring obese women to either lose weight or gain no weight during pregnancy.

I've discussed this before, but considering how common this advice is becoming, I decided this one deserves the award for Idiotic Trend of the Year.

The Offending Comment

"Now, if you didn't notice, you're obese.  You should have tried to lose the weight before getting pregnant, but since you didn't, you should lose weight now.  All of *MY* girls end up weighing at least 15 pounds less and looking much better."  -OB to large-sized mother, as documented on My OB Said What!?!

There are just so many things wrong with this comment, on so many levels.

We could certainly start with the patronizing tone of this doctor and how he calls adult women "girls." What are we, back in the 1950s?  Who in the modern world still thinks it's okay to refer to adult women as "girls"?  Talk about sexist. Talk about infantilizing grown women.

Or we could rant about how he calls his patients "my girls"........gah!!! Could he possibly be more patronizing? Since when did women become his personal property?

Or we could talk about his emphasis on "looking better" (as if that should be a primary concern of women at all, and as if that is automatic with losing weight).  How shallow.

Sexist, infantilizing, shallow, and controlling. What a winner. Feh. Obviously, this doctor is a patronizing misogynistic ass and I pity anyone under his care.  Ugh.

Some folks would shrug this off as nothing more than a whacko comment from a moron. Well, it certainly is that, but this comment is also troubling because it reflects the increasingly common recommendation for fat women to deliberately to gain very little weight or even lose it during pregnancy.

The media has picked up this advice and now often promotes the idea of dieting during pregnancy, rarely questioning it. I find that alarming, given that very low gain/gestational weight loss is associated with distinct risks in the research.

So for our Fifth Annual Turkey Awards, let's focus on the issue of  pressure for very low gain/gestational weight loss, or what I call Prenatal Weight Restriction Extremism.

Does Very Low Gain Improve Outcomes?

It's true that women of size are at increased risk for complications during pregnancy.  Although most women of size have healthy pregnancies and babies, care providers are justifiably concerned about those that do experience complications. Thus, a big push in maternity care has been looking for the silver bullet that will prevent complications in obese women.

Most care providers approach this by trying to strictly limit prenatal weight gain.  The old Institute of Medicine guidelines were at least 15 lbs. for obese women, but many doctors informally considered 25 lbs. to be the upper limit. The new IOM guidelines are 11-20 lbs. for all obese women, not currently differentiated by obesity class (class I = BMI 30-35, class II = BMI 35-40, class III = BMI 40 and above).

However, many researchers and care providers are now strongly pressing for even lower weight gain guidelines for obese women, differentiated by level of obesity, with some calling for little to no weight gain or even weight loss during pregnancy.

Proponents of this approach point to research  that shows that excessive weight gain is associated with more complications in several studies.  They also point out that those who gained less had fewer complications like pre-eclampsia, cesareans and big babies.

However, this doesn't mean that deliberately restricting weight gain prevents these complications. Remember, correlation does not equal causation.  As Nohr 2008 states,

Any causal interpretation of the association between total weight gain and these complications is limited.  For preeclampsia, high total gain most likely reflects pathologic fluid retention as part of the disease.

In other words, just because very low gain/weight loss is associated with less pre-eclampsia, it does not follow that making women lose weight during pregnancy will prevent pre-eclampsia.  Instead, higher weight gain is usually simply a side effect of pre-eclampsia due to edema.

As for cesareans, the exaggerated fear around obesity, bias about weight gain, and concern about "big babies" means that iatrogenic (provider) factors muddle the cesarean rates in this group.

There are high rates of induction of labor of obese women, induction with a lower Bishop's Score (which is less likely to succeed), and a lower threshold for surgery in women of size.  Furthermore, many providers believe that any gain in pregnancy means a big baby, and the mere suspicion of a big baby strongly increases the cesarean rate.

Since few providers are blinded to their clients' weight gains, iatrogenic factors can be significant. It certainly doesn't mean that higher gains somehow "prevent" vaginal birth.

The only really important result that can be strongly tied to prenatal weight gain is the number of babies who are born large-for-gestational-age (LGA).  However, some researchers are beginning to question even this.

Unfortunately, what care providers are ignoring is that very low gains/gestational weight loss increase other risks, and this may offset any benefits from low gains.

Is Very Low Gain or Gestational Weight Loss Safe?

Some providers argue that studies have documented obese women who have gained little weight or lost weight in pregnancy without serious consequences.  They then generalize this finding and conclude it is safe for all fat women to do so.  But their reasoning is faulty.

Yes, some women of size do naturally gain little weight during pregnancy (or even lose a bit) despite normal intake, probably because of a change in metabolism during pregnancy. A little loss is not always dangerous; some women tolerate it well. Women of size who naturally lose a little bit need to be reassured that as long as they are eating well and baby is growing okay, things will probably be fine.

However, the coincidental gestational weight loss that some women experience despite normal eating is NOT the same as telling women to deliberately aim for weight loss during pregnancy. 

You simply cannot take outcomes in women who lose weight coincidentally in pregnancy and assume you will have similar outcomes in women who restrict significantly in order to gain little or lose weight in pregnancy.  You may well have very different results.

In addition, there is significant amount of research showing that very low gain and/or gestational weight loss (GWL) increases the risks of several poor outcomes.  Media reports promoting low/GWL are disingenuous in ignoring these studies.

For example, Bayerlein 2011 shows that gestational weight loss increases the risk for small-for-gestational-age (SGA) babies and prematurity in all but the very heaviest women.  And even in the "morbidly obese" group, other studies show that gestational weight loss or very low gain may still increase the risk for SGA babies and/or prematurity, including:

• Blomberg 2011 - increased risk for SGA with GWL even among class III obese women
• Bodnar 2010 - GWL increased risk for SGA and preterm births among obese women
• Dietz 2006 - very low weight gain doubled the risk for very preterm births even among class II obese women and higher 
• Vesco 2011 - weight gain below the IOM guidelines in obese women nearly quadrupled the rate of SGA babies
• Potti 2010 - rates of preterm birth, low birthweight babies, and NICU admissions were higher with gains lower than the IOM guidelines
• Hasegawa 2012 - GWL was associated with SGA and preterm births, as well as several other indicators of suboptimal outcome

These are not random findings.  Not every study has found problems, but this many studies finding a pattern of growth restriction or prematurity shows that there is significant reason for concern with prenatal weight restriction extremism.

This is important because SGA babies face higher risks for many complications, both in the beginning and as they age.  

For example, SGA babies are at risk for fetal death, sudden infant death, cognitive delay, and poor neurodevelopmental outcomes.

SGA may also play a role in development of adult disease, since SGA babies are much more at-risk for insulin-resistance, metabolic syndrome, and other issues as they age, even when compared with LGA babies.

In addition, very low weight gain is also associated with higher incidence of prematurity and even stillbirth in some studies. And some research shows that SGA babies of obese women are at particular risk for stillbirth.

Recommending that women of size (especially mid-sized fat women) lose weight in pregnancy probably significantly increases the chances that many will have a less healthy child, yet many care providers blithely shrug this off and continue to demand that their obese patients gain little weight or even lose weight.

Diets vs. Healthy Lifestyles

Of course, some providers will protest that they are not telling women to diet, just trying to get them to eat more healthfully and to get more exercise as a way to limit excessive prenatal weight gain. All well and good, as long as the program is reasonable.

Programs that gently promote reasonable nutrition and getting regular exercise in pregnancy are fine, as long as they don't indulge in shaming or encourage disordered eating behaviors. My only argument is that these programs should apply to all women (not just fat women) since poor lifestyle habits can be found in every body size, but I'm never opposed to emphasizing proactive habits.  Would that more care providers spent more time on sensible nutrition and encouraged exercise!

However, I do have a problem with programs or care providers who are telling fat women to deliberately aim for no weight gain or weight loss in pregnancy, to restrict their calories significantly, or to cut out entire groups of food (carbs, dairy, fruit, etc.).  This is an entirely different form of intervention and one that is dangerous. And it is happening.  Researchers cannot shrug these stories off as a few rogue doctors who are overreacting to the issue.

Some researchers will point out that many of the studies have been about improving nutrition and exercise, not about "dieting."  However, look at the story headlines that accompany the reporting on these studies:

"Obese Pregnant Women Should Go On a Diet"
"Diets Suggested for More Pregnant Women"
"Obese Pregnant Women Can Safely Diet: Study"
"Obese and Pregnant: Dieting Safe for Mom, Baby"
"OK If Obese Pregnant Women Lose Weight"
"It Can Be Safe ─ and Beneficial ─ to Diet While Pregnant"

The headlines in these articles imply more than just improved nutrition, they explicitly use the word "diet" ─ which to most people means significant restriction of calories and foods.  What take-home message do you think women are going to get when they read these headlines?

If researchers keep promoting in the media the idea that dieting and weight loss is "safe"  or "OK" in pregnancy, then many providers and mothers will hear that not just as "cut out junk food" but also as "restrict calories" or "cut out all carbs" etc.  And that's dangerous.

Many providers give strict admonishments to gain no weight, with the implication that this is to be attained at whatever cost, with overly simplistic advice on how to achieve this.  This sets women up for failure, harassment and punitive treatment when most fail to achieve the objective.  As one women of size noted:

Although my OB is a decent man, he constantly hammers me about my weight (I've lost 3 lbs. during this pregnancy so far), and I am scared to death to step on the scales at my appointments.

Is Extreme Weight Restriction a Realistic Goal?

Care providers are creating dangerous expectations for women, demanding an almost impossible goal of no gain or weight loss in pregnancy.  Just because some obese women have had extremely low gains in pregnancy, researchers are assuming that most can, and this just doesn't bear up to scrutiny.

Generally speaking, most obese women gain around 5-30 lbs. in pregnancy, though research shows that gestational weight gain is highly variable in women of size, much more variable than in other women.

Recent research suggests that the optimal gain may depend on the degree of obesity (class I obese women may need to gain on the higher end of the IOM range or a little more, and class III obese women may benefit from gaining on the lower end of that range or even slightly less).

But of course, these are generalizations only and the main emphasis should be on good nutrition and reasonable exercise, not on rigid weight gain goals.

Some obese women do gain more than recommended (especially those with recent weight loss, chronic dieters, those who develop preeclampsia, or those who overindulge).  Very large gains, as noted before, are associated with poorer outcomes and therefore are a source of concern. However, a larger gain doesn't doesn't necessarily indicate poor outcomes if the mother is getting good nutrition from healthy foods.  Sometimes people just gain in unpredictable ways.

Quite a few women of size lose weight at first and then regain back to a small total surplus by term.  (I'm one of these.) As long as they are eating well and baby is growing well, it's not a big concern.

Although not common, some women of size do end up with a net weight loss by term.  However, it's hard to document how many because many studies lump "low weight gain" in with "gestational weight loss." So it can be tricky to document exactly how many women really are losing weight during pregnancy.

Edwards 1996 showed that about 11% of obese women either did not gain weight or lost weight during pregnancy. Note that they don't separate "no gain" from a net loss, so it's hard to know how many really lost weight.  Still, that means that about 89% of obese women naturally did gain weight in pregnancy. So is universal gestational weight loss in obese women truly a realistic goal?

In the Edwards study, obese women who lost or gained no weight had a higher incidence of SGA babies.  They found that the weight gain that was associated with the best outcome was 15-25 lbs. However, they did not stratify optimal weight gains by obesity class.

In Bayerlein 2011, results were pulled from a large birth registry, weight gains were stratified by level of obesity, and there was information about how many actually lost weight (vs. those who stayed the same or had a small gain).  Here are their results:

• 0.6% of "overweight" women lost weight in pregnancy
• 1.8% of Class I obese (BMI 30-35) women lost weight in pregnancy
• 4.1% of Class II obese (BMI 35-40) women lost weight in pregnancy
• 8.8% of Class III obese (BMI 40 and above) women lost weight in pregnancy

The total percentage of obese women who actually lost weight during pregnancy was only 3% (if we lump all classes of obesity together in the study).

In other words, about 97% of obese women in this very large study gained at least some weight in pregnancy. Even in the most obese group (BMI of 40 or more), 91% of women gained at least some weight in pregnancy.

This shows that the increasing emphasis on no gain/GWL as a weight gain goal for obese women is probably extremely unrealistic.  It sets women up for failure from the start, and makes them feel guilty for something they may not be able to help.

Of course, critics would say that if these women just tried harder or had better nutritional guidance, more could lose weight.  This may be true for some, but it wouldn't be true for all, and probably not even most.

And since most obese women naturally gain at least some weight in pregnancy, what kind of draconian restrictions would have to be followed in order to make most not gain weight or even lose weight?

How restrictive is too restrictive, and what happens with even "mild" restrictions?  What research is there to determine the long-term safety of restricted diets in pregnancy?  What unintended consequences might result?  What might the downstream results be for the babies of those women forced to lose weight who would not otherwise lose weight?

To force the 89% - 97% of obese women who naturally gain some weight in pregnancy into losing weight across the board, like the doctor in our original comment wants ("all of MY girls end up weighing at least 15 lbs. less") by whatever means needed, is foolish, short-sighted, and unethical.

While promoting extreme prenatal weight restriction will probably decrease the number of LGA babies in high-BMI women, the studies below suggest it will likely be paid for by increasing the number of SGA and premature babies. Since these babies have more short-term and long-term health problems, that's too high a price.

Providers are playing a dangerous game of Russian Roulette with babies by pressuring high-BMI women towards extreme weight gain restrictions.

Final Thoughts

How much weight obese women should gain during pregnancy is a very hot topic in obstetric research now. Care providers love the idea that risks in the pregnancies of women of size could be magically resolved by simply limiting weight gain.

Although it's clear that very high gains are associated with risks and that most obese women don't need to gain quite as much as other women, it's not yet clear what the most optimal gain is for women of size.  It may depend on the degree of obesity. More importantly, it should be based on nutrition rather than rigid weight gain goals.

However, some care providers and researchers are distorting weight gain research to promote an extreme weight gain restriction agenda, conveniently ignoring studies that suggest that there are risks associated with this.

This is reflected in the press releases surrounding these studies.  It's not enough that fat women be kept to lower weight gains than other women; now the media articles are promoting "diets," no gain, and even weight LOSS. Look at the headlines accompanying the articles about restricted weight gain in pregnancy:

"Overweight Pregnant Women SHOULD Be Put On a Diet, Doctors Say"
"Dieting During Pregnancy 'Could Be Beneficial To Woman's Health'"
"Obese Women Should Not Gain Weight During Pregnancy"
"New Goal for the Obese: Zero Gain in Pregnancy"
"Expectant? How Much Weight Should You Lose?"

"Pregnancy Weight Loss Can Be Safe For Obese Women"

"Study: Severely Obese Women Should Lose Weight During Pregnancy"

These are irresponsible, given the fact that research that shows some major areas for concern with extreme restriction.

Come on, providers. I know many of you have very good intentions and want only the best outcomes for your high-BMI clients. I know many of you have been taught that strictly limiting prenatal weight gain will help obese women have better outcomes, but think this through.  Avoiding large weight gains  or encouraging modestly lower weight gain is far different than pressuring women to gain no weight or to lose weight in pregnancy.

Yes, some women of size do experience low gains or a little weight loss in pregnancy without disastrous results. However, we do not know that the same relatively benign results will occur with telling women to deliberately try to lose weight or gain nothing during pregnancy.

And when we strongly restrict gain or tell women to deliberately lose weight in pregnancy, we raise the risk for SGA babies or premature babies, which bring a whole host of far more ominous health risks.

It is reasonable for providers to be concerned over excessive gains in pregnancy, but this concern should be addressed by emphasizing reasonable nutrition and regular exercise only, not by emphasizing massive (and unrealistic) restriction of weight gain.

I have no problem with providers emphasizing healthy foods and reasonable intake in pregnancy, and am all for encouraging pregnant women to get more exercise/movement in pregnancy.  These will likely lead to healthier pregnancies and babies.

And if a healthy intake and more exercise leads to a somewhat smaller overall gain, that's okay with me.  In a few women, it might even lead to a small loss, depending on what their habits were like before pregnancy and how their metabolism changes during pregnancy. That doesn't have to be unhealthy or abnormal.

But there's a difference between promoting healthy eating and exercise in pregnancy and telling fat women to "diet" in pregnancy, harassing them about every bite they eat, or promoting extreme gain restriction. Yet that is what is happening to many women of size now:

• “Your weight looks great, good job!…But you should eat nothing but vegetables for the rest of the pregnancy.”–Midwife to a mother at a 20 week prenatal appointment [found here]
• “I’d be happy if you didn't gain any weight at all during your pregnancy.”–OB to mother who expressed concerned that she had lost weight during her second trimester [found here]
• “You should not gain any more weight from here on out. You've gained plenty. The baby will grow off of what you have.”-OB Medical Assistant to mom at 24 weeks gestation. It was the first appointment the mom had gained instead of lost weight in her pregnancy [found here]

These media articles that tell women that it's "safe" to diet or to lose weight in pregnancy are misleading, and researchers who promote this are cherry-picking the research.  In fact, there is substantial room for concern about very low gain and gestational weight loss, even in very obese women.

The anorexation of prenatal weight gain standards must stop. Care providers, if you are concerned about a woman's weight gain, monitor fetal growth patterns and emphasize excellent nutrition. Remember that most of the time, reasonable habits will produce a weight gain that is appropriate for that particular woman.

Stop promoting extreme prenatal weight gain restriction and instead focus on promoting reasonable nutrition and exercise.


References

Risks of Gestational Weight Loss or Very Low Gains

Obstet Gynecol. 2007 Oct;110(4):752-8. Gestational weight gain and pregnancy outcomes in obese women: how much is enough? Kiel DW, Dodson EA, Artal R, Boehmer TK, Leet TL. PMID: 17906005

Source

OBJECTIVE: To examine the effect of gestational weight change on pregnancy outcomes in obese women. METHODS: A population-based cohort study of 120,251 pregnant, obese women delivering full-term, liveborn, singleton infants was examined to assess the risk of four pregnancy outcomes (preeclampsia, cesarean delivery, small for gestational age births, and large for gestational age births) by obesity class and total gestational weight gain. RESULTS: Gestational weight gain incidence for overweight or obese pregnant women, less than the currently recommended 15 lb, was associated with a significantly lower risk of preeclampsia, cesarean delivery, and large for gestational age birth and higher risk of small for gestational age birth. These results were similar for each National Institutes of Health obesity class (30-34.9, 35-35.9, and 40.0 kg/m(2)), but at different amounts of gestational weight gain. CONCLUSION: Limited or no weight gain in obese pregnant women has favorable pregnancy outcomes.  [Kmom note: Despite the increased risk for SGA, the study recommended weight gains of 10-25 lbs. for class I obese women, 0-9 lbs. for class II obese women, and a weight loss of 0-9 lbs. for class III obese women.]

BJOG. 2011 Jan;118(1):55-61. doi: 10.1111/j.1471-0528.2010.02761.x. Associations of gestational weight loss with birth-related outcome: a retrospective cohort study. Beyerlein A, et al. PMID: 21054761 

SETTING AND POPULATION: Data on 709 575 singleton deliveries in Bavarian obstetric units from 2000-2007 were extracted from a standard dataset for which data are regularly collected for the national benchmarking of obstetric units. METHODS: We calculated the odds ratios (ORs) for adverse pregnancy outcome by GWL (explanatory variable) compared with nonexcessive weight gain with adjustment for confounders and stratification by BMI category (underweight, BMI < 18.5 kg/m²; normal weight, BMI = 18.5-24.9 kg/m²; overweight, BMI = 25-29.9 kg/m²; obese class I, BMI = 30-34.9 kg/m²; obese class II, BMI = 35-39.9 kg/m²; obese class III, BMI ≥ 40 kg/m²). MAIN OUTCOME MEASURES: Pre-eclampsia, nonelective caesarean section, preterm delivery, small or large for gestational age (SGA/LGA) birth and perinatal mortality. RESULTS: GWL was associated with a decreased risk of pregnancy complications, such as pre-eclampsia and nonelective caesarean section, in overweight and obese women [e.g. OR = 0.65 (95% confidence interval: 0.51, 0.83) for nonelective caesarean section in obese class I women]. The risks of preterm delivery and SGA births, by contrast, were significantly higher in overweight and obese class I/II mothers [e.g. OR = 1.68 (95% confidence interval: 1.37, 2.06) for SGA in obese class I women]. In obese class III women, no significantly increased risks of poor outcomes for infants were observed. CONCLUSIONS: The association of GWL with a decreased risk of pregnancy complications appears to be outweighed by increased risks of prematurity and SGA in all but obese class III mothers.

Obstet Gynecol. 2011 May;117(5):1065-70. Maternal and neonatal outcomes among obese women with weight gain below the new Institute of Medicine recommendations. Blomberg M. PMID: 21508744 

METHODS: This was a population-based cohort study, which included 32,991 obesity class I, 10,068 obesity class II, and 3,536 obesity class III women who were divided into four gestational weight gain categories. Women with low (0-4.9 kg) or no gestational weight gain were compared with women gaining the recommended 5-9 kg concerning obstetric and neonatal outcome after suitable adjustments. RESULTS: Women in obesity class III who lost weight during pregnancy had a decreased risk of cesarean delivery (24.4%; odds ratio [OR] 0.77, 95% confidence interval [CI] 0.60-0.99), large-for-gestational-age births (11.2%, OR 0.64, 95% CI 0.46-0.90), and no significantly increased risk for pre-eclampsia, excessive bleeding during delivery, instrumental delivery, low Apgar score, or fetal distress compared with obese (class III) women gaining within the Institute of Medicine recommendations. There was an increased risk for small for gestational age, 3.7% (OR 2.34, 95% CI 1.15-4.76) among women in obesity class III losing weight, but there was no significantly increased risk of small for gestational age in the same group with low weight gain. CONCLUSION: Obese women (class II and III) who lose weight during pregnancy seem to have a decreased or unaffected risk for cesarean delivery, large for gestational age, pre-eclampsia, excessive postpartum bleeding, instrumental delivery, low Apgar score, and fetal distress. The twofold increased risk of small for gestational age in obesity class III and weight loss (3.7%) is slightly above the overall prevalence of small-for-gestational-age births in Sweden (3.6%).

Epidemiology. 2006 Mar;17(2):170-7. Combined effects of prepregnancy body mass index and weight gain during pregnancy on the risk of preterm delivery. Dietz PM, et al. PMID: 16477257

...METHODS: Using data from the Pregnancy Risk Assessment Monitoring System in 21 states, we estimated the risk of very (20-31 weeks) and moderately (32-36 weeks) preterm delivery associated with a combination of prepregnancy body mass index (BMI) and gestational weight gain among 113,019 women who delivered a singleton infant during 1996-2001. We categorized average weight gain (kilograms per week) as very low (<0.12), low (0.12-0.22), moderate (0.23-0.68), high (0.69-0.79), or very high (>0.79). We categorized prepregnancy BMI (kg/m) as underweight (<19.8), normal (19.8-26.0), overweight (26.1-28.9), obese (29.0-34.9), or very obese (>or=35.0)...RESULTS: There was a strong association between very low weight gain and very preterm delivery that varied by prepregnancy BMI, with the strongest association among underweight women (adjusted odds ratio = 9.8; 95% confidence interval = 7.0-13.8) and the weakest among very obese women (2.3; 1.8-3.1). Very low weight gain was not associated with moderately preterm delivery for overweight or obese women. Women with very high weight gain had approximately twice the odds of very preterm delivery, regardless of prepregnancy BMI. CONCLUSIONS: This study supports concerns about very low weight gain during pregnancy, even among overweight and obese women, and also suggests that high weight gain, regardless of prepregnancy BMI, deserves further investigation.

Am J Clin Nutr. 2010 Jun;91(6):1642-8. Epub 2010 Mar 31. Severe obesity, gestational weight gain, and adverse birth outcomes. Bodnar LM, et al. PMID: 20357043

...OBJECTIVE: We explored associations between gestational weight gain and small-for-gestational-age (SGA) births, large-for-gestational-age (LGA) births, spontaneous preterm births (sPTBs), and medically indicated preterm births (iPTBs) among obese women who were stratified by severity of obesity. DESIGN: We studied a cohort of singleton, live-born infants without congenital anomalies born to obesity class 1 (prepregnancy body mass index [BMI (in kg/m(2))]: 30-34.9; n = 3254), class 2 (BMI: 35-39.9; n = 1451), and class 3 (BMI: > or =40; n = 845) mothers. We defined the adequacy of gestational weight gain as the ratio of observed weight gain to IOM-recommended gestational weight gain. RESULTS: The prevalence of excessive gestational weight gain declined, and weight loss increased, as obesity became more severe. Generally, weight loss was associated with an elevated risk of SGA, iPTB, and sPTB, and a high weight gain tended to increase the risk of LGA and iPTB. Weight gains associated with probabilities of SGA and LGA of less than or =10% and a minimal risk of iPTB and sPTB were as follows: 9.1-13.5 kg (obesity class 1), 5.0-9 kg (obesity class 2), 2.2 to less than 5.0 kg (obesity class 3 white women), and less than 2.2 kg (obesity class 3 black women). CONCLUSION: These data suggest that the range of gestational weight gain to balance risks of SGA, LGA, sPTB, and iPTB may vary by severity of obesity.

Obstet Gynecol. 2011 Apr;117(4):812-8. Newborn size among obese women with weight gain outside the 2009 Institute of Medicine recommendation. Vesco KK, et al. PMID: 21422851

OBJECTIVE: To estimate risk of delivering macrosomic, large-for-gestational-age and small-for-gestational-age neonates in obese women with gestational weight gain outside the 2009 Institute of Medicine recommendation (11-20 pounds). METHODS: In a retrospective cohort study, we evaluated 2,080 obese women (body mass index 30 or higher) with singleton pregnancies that resulted in term live births within one health maintenance organization between 2000 and 2005; women with diabetes or hypertensive disorders were excluded. Gestational weight gain was categorized as less than 0, 0 to less than 11, 11-20 (referent), greater than 20-30, greater than 30-40, and greater than 40 pounds and as above, below, or within Institute of Medicine recommendations. We conducted multivariable logistic regression to estimate the odds of large for gestational age and small for gestational age (birth weights greater than the 90th percentile and less than the 10th percentile for gestational age, respectively) and macrosomia (greater than 4,500 g) adjusting for potential confounders. RESULTS: Eighteen percent gained below, 25% within, and 57% above Institute of Medicine recommendations. Prevalence of macrosomia, large for gestational age, and small for gestational age were 4.3%, 19.8%, and 4.3%, respectively. Compared with weight gain of 11-20 pounds, weight gain above recommendations did not significantly decrease small-for-gestational-age risk but was associated with increased odds of macrosomia (adjusted odds ratio [OR] 3.36; 95% confidence interval [CI] 1.74-6.51; 6.0% compared with 2.1%) and large for gestational age (adjusted OR 1.80; 95% CI 1.36-2.38; 23.8% compared with 16.6%). Weight gain below recommendations was associated with increased odds of small for gestational age (adjusted OR 3.94; 95% CI 2.04-7.61; 8.8% compared with 2.7%) and decreased odds of large for gestational age (adjusted OR 0.56; 95% CI 0.37-0.84; 11.2% compared with 16.6%). CONCLUSION: Regarding small for gestational age and large for gestational age, there is no benefit of weight gain above Institute of Medicine recommendations. Weight gain below recommendations decreases large for gestational age but increases small-for-gestational-age risk.

J Matern Fetal Neonatal Med. 2012 Oct;25(10):1909-12. doi: 10.3109/14767058.2012.664666. Epub 2012 Mar 12. Gestational weight loss has adverse effects on placental development. Hasegawa J, Nakamura M, Hamada S, Okuyama A, Matsuoka R, Ichizuka K, Sekizawa A, Okai T. PMID: 22348351

Source

OBJECTIVE: To clarify whether mothers with gestational weight loss (GWL) were likely to have adverse effects on the placenta. STUDY DESIGN: Subjects who delivered viable singleton infants after 24 weeks of gestation were enrolled. A retrospective analysis to evaluate cases of GWL in association with the findings of the placenta and amniotic membrane after delivery was conducted. After consideration of confounders, a case-control study with matched pairs (1:2) was performed. RESULTS: Of all subjects (5551 cases), 83 cases (1.5%) with GWL were found. Since the pre-pregnancy maternal body mass index (BMI) was significantly higher in cases, 166 controls with a matched BMI were selected. The neonatal birth weights, placental weights and the umbilical cord length in cases were significantly smaller than in controls (p < 0.05). Preterm delivery and small for gestational age (SGA) infants were more frequently observed in cases compared with controls [odds ratio (OR) 6.3; 95% confidence interval (CI) 3.3, 12.1, OR 4.3; 95% CI 1.9, 9.9]. pPROM were observed in 10.8% of the cases and 1.8% of the control (OR 6.6; 95% CI 1.7, 25.1). However, the frequencies of chorioamnionitis and the cervical length at second trimester were not different between the two groups. CONCLUSION: GWL is associated with SGA, small placenta, short umbilical cord length, preterm delivery and pPROM.

Am J Perinatol. 2010 May;27(5):415-20. Obstetric outcomes in normal weight and obese women in relation to gestational weight gain: comparison between Institute of Medicine guidelines and Cedergren criteria. Potti S, Sliwinski CS, Jain NJ, Dandolu V. PMID: 20013574

We compared obstetric outcomes based on gestational weight gain in normal-weight and obese women using traditional Institute of Medicine (IOM) guidelines and newly recommended Cedergren criteria...among obese patients, when compared with IOM guidelines, macrosomia (10.79% versus 5.47%) and cesarean delivery rates (43.95% versus 40.71%) were lower using Cedergren criteria but the rates of preterm delivery (6.83% versus 8.32%), low birth weight (0.87% versus 1.88%), and NICU admissions (8.92% versus 13.78%) were higher with the Cedergren criteria.  Based on our results, ideal gestational weight gain is presumably somewhere between the IOM and Cedergren's guidelines.

Risk of Excessive Weight Gain in Obese Women

Am J Clin Nutr. 2008 Jun;87(6):1750-9. Combined associations of prepregnancy body mass index and gestational weight gain with the outcome of pregnancy.  Nohr EA, Vaeth M, Baker JL, Sørensen TIa, Olsen J, Rasmussen KM. PMID: 18541565

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...OBJECTIVES: We aimed to investigate the combined associations of prepregnancy BMI and GWG with pregnancy outcomes and to evaluate the trade-offs between mother and infant for different weight gains. DESIGN: Data for 60892 term pregnancies in the Danish National Birth Cohort were linked to birth and hospital discharge registers. Self-reported total GWG was categorized as low (<10 kg), medium (10-15 kg), high (16-19 kg), or very high (>or=20 kg)...RESULTS: High and very high GWG added to the associations of high prepregnancy BMI with cesarean delivery and were strongly associated with high postpartum weight retention. Moreover, greater weight gains and high maternal BMI decreased the risk of growth restriction and increased the risk of the infant's being born large-for-gestational-age or with a low Apgar score. Generally, low GWG was advantageous for the mother, but it increased the risk of having a small baby, particularly for underweight women. CONCLUSIONS: Heavier women may benefit from avoiding high and very high GWG, which brings only a slight increase in the risk of growth restriction for the infant....

Am J Perinatol. 2010 Apr;27(4):333-8. doi: 10.1055/s-0029-1243304. Epub 2009 Dec 10. Excessive weight gain among obese women and pregnancy outcomes. Flick AA, Brookfield KF, de la Torre L, Tudela CM, Duthely L, González-Quintero VH. PMID: 20013581  full text at: http://www.advancedmfm.com/wp-content/uploads/2010/06/Flickpdf.pdf

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...A retrospective study was performed on all obese women. Outcomes included rates of preeclampsia (PEC), gestational diabetes, cesarean delivery (CD), preterm delivery, low birth weight, very low birth weight, macrosomia, 5-minute Apgar score of <7, and neonatal intensive care unit (NICU) admission and were stratified by body mass index (BMI) groups class I (BMI 30 to 35.9 kg/m(2)), class II (36 to 39.9 kg/m(2)), and class III (>or=40 kg/m(2)). Gestational weight change was abstracted from the mother's medical chart and was divided into four categories: weight loss, weight gain of up to 14.9 pounds, weight gain of 15 to 24.9 pounds, and weight gain of more than 25 pounds. A total 20,823 obese women were eligible for the study. Univariate analysis revealed higher rates of preeclampsia, gestational diabetes, Cesarean deliveries, preterm deliveries, low birth weight, macrosomia, and NICU admission in class II and class III obese women when compared with class I women. When different patterns of weight gain were used as in the logistic regression model, rates of PEC and CD were increased. Excessive weight gain among obese women is associated with adverse outcomes with a higher risk as BMI increases. [Kmom note: The study results show a clear trend towards more premature and low birthweight babies among the obese women who lost or gained very little pregnancy weight, but the numbers were not enough to reach statistical significance, so the trend is not even commented on in the study.]

Prevalence of Gestational Weight Loss in Obese Women

Obstet Gynecol. 1996 Mar;87(3):389-94. Pregnancy complications and birth outcomes in obese and normal-weight women: effects of gestational weight change. Edwards LE, et al. PMID: 8598961

...METHODS: Multivariate logistic regression described the relation of weight change to pregnancy course and outcomes in a retrospective study of 683 obese and 660 normal-weight women who delivered singleton living neonates. RESULTS: Compared with normal-weight women, obese women gained an average of 5 kg (11 lb) less during pregnancy and were more likely to lose or gain no weight (11% versus less than 1%). Obese women were significantly more likely to have pregnancy complications, but the incidence of complications was not associated with weight change. Compared with obese women who gained 7-11.5 kg (15-25 lb), obese women who lost or gained no weight were at higher risk for delivery of infants under 3000 g or small for gestational age infants, and those who gained more than 16 kg (35 lb) were at twice the risk for delivery of infants who were 4000 g or heavier. CONCLUSION: Gestational weight change was not associated with pregnancy complications in obese or normal-weight women. To optimize fetal growth, weight gains of 7-11.5 kg (15-25 lb) for obese women and 11.5-16 kg (25-35 lb) for normal-weight women appear to be appropriate.

*See also Bayerlein 2011, above

Short-Term Risks of Small-For-Gestational-Age

Am J Obstet Gynecol. 1998 Apr;178(4):658-69. Impaired growth and risk of fetal death: is the tenth percentile the appropriate standard? Seeds JW, Peng T. PMID: 9579427

OBJECTIVE: Our purpose was to determine whether the 10th percentile of birth weight for gestational age is appropriate to identify fetuses at risk of death associated with impaired growth. STUDY DESIGN: All live births recorded in Virginia from Jan. 1, 1991, through Dec. 31, 1993, were examined...RESULTS: Significantly elevated fetal mortality was found for birth weights through the 15th percentile. The odds ratio for fetal mortality relative to the baseline for births < or = 5th percentile was 5.6, for the 5th through the 10th percentile 2.8, and for the 10th through the 15th percentile 1.9. These were all significant. CONCLUSION: Fetuses with birth weights between the 10th and 15th percentiles are at a significantly increased risk for fetal death. Therefore the use of the 15th percentile as a diagnostic threshold for the identification of the fetus at increased risk associated with impaired growth is recommended.

Arch Dis Child Fetal Neonatal Ed. 1997 Mar;76(2):F75-81. Differential effects of preterm birth and small gestational age on cognitive and motor development. Hutton JL, Pharoah PO, Cooke RW, Stevenson RC. PMID: 9135284

AIMS: To determine the differential effects of preterm birth and being small for gestational age on the cognitive and motor ability of the child...CONCLUSIONS: The effects of SGA and preterm birth differed: SGA was associated with cognitive ability, as measured by IQ and reading comprehension;motor ability was additionally associated with preterm birth....

Ultrasound Obstet Gynecol. 2012 Sep;40(3):267-75. doi: 10.1002/uog.11112. Epub 2012 Aug 7. Neurodevelopmental delay in small babies at term: a systematic review. Arcangeli T, Thilaganathan B, Hooper R, Khan KS, Bhide A. PMID: 22302630

OBJECTIVE: Being small for gestational age (SGA) or having fetal growth restriction (FGR) may be associated with poorer neurodevelopmental outcomes compared to being appropriate for gestational age (AGA)...METHODS: Studies of neurodevelopment in SGA/FGR babies were identified from a search of the internet scientific databases. Studies that included preterm births and those that did not define absolute indices of standardized cognitive outcome were excluded...CONCLUSION: The findings of the study demonstrate that among babies born at term, being SGA is associated with lower scores on neurodevelopmental outcomes compared to AGA controls. A trial designed to evaluate the effects of intervention in small fetuses born at term in order to improve the neurodevelopmental outcome is urgently needed.

Arch Dis Child Fetal Neonatal Ed. 2007 Nov;92(6):F473-8. Epub 2007 Feb 21. Size for gestational age at birth: impact on risk for sudden infant death and other causes of death, USA 2002. Malloy MH. PMID: 17314115

BACKGROUND: Small for gestational age (SGA) infants have been reported to be at higher risk for sudden infant death syndrome (SIDS). OBJECTIVE: To compare the risk of SIDS among SGA and large for gestational age (LGA) infants with that of death from other causes of sudden unexpected deaths in infancy (SUDI) and the residual "other" causes of infant death. METHODS: The 2002 US period infant birth and death certificate linked file was used to identify infant deaths classified as SIDS (ICD-10 code R95), SUDI (ICD-10 codes R00-Y84 excluding R95) or all other residual codes...CONCLUSION: Although SGA infants seem to be at slightly increased risk for SIDS or SUDI their risk for "other" residual causes is about 2.5 times higher. LGA infants seem to be at reduced risk of mortality for all causes. The mechanisms by which restricted intrauterine growth increases risk of mortality and excessive intrauterine growth offers protective effects are uncertain.

Am J Perinatol. 2012 Feb;29(2):87-94. doi: 10.1055/s-0031-1295647. Epub 2011 Nov 30. Neonatal outcomes of small for gestational age preterm infants in Canada. Qiu X, Lodha A, Shah PS, Sankaran K, Seshia MM, Yee W, Jefferies A, Lee SK; Canadian Neonatal Network. PMID: 22131047

To compare the effect of small for gestational age (SGA) on mortality, major morbidity and resource utilization among singleton very preterm infants (<33 weeks gestation) admitted to neonatal intensive care units (NICUs) across Canada. Infants admitted to participating NICUs from 2003 to 2008 were divided into SGA (defined as birth weight <10th percentile for gestational age and sex) and non-small gestational age (non-SGA) groups...SGA infants (n = 1249 from a cohort of 11,909) had a higher odds of mortality (adjusted odds ratio [AOR] 2.46; 95% confidence interval [CI], 1.93-3.14), necrotizing enterocolitis (AOR 1.57; 95% CI, 1.22-2.03), bronchopulmonary dysplasia (AOR 1.78; 95% CI, 1.48-2.13), and severe retinopathy of prematurity (AOR 2.34; 95% CI, 1.71-3.19). These infants also had lower odds of survival free of major morbidity (AOR 0.50; 95% CI, 0.43-0.58) and respiratory distress syndrome (AOR 0.79; 95% CI, 0.68-0.93). In addition, SGA infants had a more prolonged stay in the NICU, and longer use of ventilation continuous positive airway pressure, and supplemental oxygen (p < 0.01 for all). SGA infants had a higher risk of mortality, major morbidities, and higher resource utilization compared with non-SGA infants.

Long-Term Risks of Small-For-Gestational-Age

Diabet Med. 2003 May;20(5):339-48. Is birth weight related to later glucose and insulin metabolism?--A systematic review. Newsome CA, et al. PMID: 12752481

AIM: To determine the relationship of birth weight to later glucose and insulin metabolism...RESULTS: Forty-eight papers fulfilled the criteria for inclusion, mostly of adults in developed countries...CONCLUSIONS: The published literature shows that, generally, people who were light at birth have an adverse profile of later glucose and insulin metabolism....

Diabetologia. 2010 May;53(5):907-13. doi: 10.1007/s00125-009-1650-y. Epub 2010 Jan 29. Independent effects of weight gain and fetal programming on metabolic complications in adults born small for gestational age. Meas T, Deghmoun S, Alberti C, Carreira E, Armoogum P, Chevenne D, Lévy-Marchal C. PMID: 20111856

AIMS/HYPOTHESIS: Insulin resistance (IR) and the metabolic syndrome (MS) have been reported in adults as a consequence of being born small for gestational age (SGA). The process seems to be initiated early in life; however, little is known about the progression of MS and IR in young adults. We hypothesised that being born SGA would promote a greater progression over time of IR and MS, reflecting not only the gain in weight and fat mass but also the extension of the fetal programming process. METHODS: Participants were selected from a community-based cohort and born full-term either SGA (birthweight <10th percentile) or appropriate for gestational age (25th < birthweight < 75th percentile). A total of 1,308 individuals were prospectively followed between the ages of 22 and 30 years. RESULTS: At both ages, individuals born SGA were more insulin-resistant and showed a significantly higher prevalence of MS. Over the 8 year follow-up, the risk of developing MS was twofold higher in those SGA, after adjustment for gain in BMI, whereas the progression of IR was not significantly affected by the birth status....

Am J Public Health. 2011 Dec;101(12):2317-24. Epub 2011 Oct 20. Early-life origins of adult disease: national longitudinal population-based study of the United States. Johnson RC, Schoeni RF. PMID: 22021306

...METHODS: Using US nationally representative longitudinal data, we estimated hazard models of the onset of asthma, hypertension, diabetes, and stroke, heart attack, or heart disease. The sample contained 4387 children who were members of the Panel Study of Income Dynamics in 1968; they were followed up to 2007, when they were aged 39 to 56 years. Our research design included sibling comparisons of disease onset among siblings with different birth weights. RESULTS: The odds ratios of having asthma, hypertension, diabetes, and stroke, heart attack, or heart disease by age 50 years for low-birth weight babies vs others were 1.64 (P < .01), 1.51 (P < .01), 2.09 (P < .01), and 2.16 (P < .01), respectively. Adult disease prevalence differed substantially by childhood socioeconomic status (SES). After accounting for childhood socioeconomic factors, we found a substantial hazard ratio of disease onset associated with low birth weight, which persisted for sibling comparisons. CONCLUSIONS: Childhood SES is strongly associated with the onset of chronic disease in adulthood. Low birth weight plays an important role in disease onset; this relation persists after an array of childhood socioeconomic factors is accounted for.

J Clin Endocrinol Metab. 2009 Nov;94(11):4448-52. doi: 10.1210/jc.2009-1079. Epub 2009 Oct 9. Obese children with low birth weight demonstrate impaired beta-cell function during oral glucose tolerance test. Brufani C, Grossi A, Fintini D, Tozzi A, Nocerino V, Patera PI, Ubertini G, Porzio O, Barbetti F, Cappa M. PMID: 19820011

OBJECTIVE: Epidemiological studies have shown an association between birth weight and future risk of type 2 diabetes, with individuals born either small or large for gestational age at increased risk. We sought to investigate the influence of birth weight on the relation between insulin sensitivity and beta-cell function in obese children. SUBJECTS AND METHODS: A total of 257 obese/overweight children (mean body mass index-sd score, 2.2 +/- 0.3), aged 11.6 +/- 2.3 yr were divided into three groups according to birth weight percentile: 44 were small for gestational age (SGA), 161 were appropriate for gestational age (AGA), and 52 were large for gestational age (LGA). Participants underwent a 3-h oral glucose tolerance test with glucose, insulin, and C-peptide measurements...CONCLUSIONS: SGA obese children fail to adequately compensate for their reduced insulin sensitivity, manifesting deficit in early insulin response and reduced disposition index that results in higher glucose AUC. Thus, SGA obese children show adverse metabolic outcomes compared to AGAs and LGAs.

Obstet Gynecol. 2009 Aug;114(2 Pt 1):333-9. doi: 10.1097/AOG.0b013e3181ae9a47. Success of programming fetal growth phenotypes among obese women. Salihu HM, Mbah AK, Alio AP, Kornosky JL, Bruder K, Belogolovkin V. PMID: 19622995

...METHODS: This was a retrospective cohort study using the Missouri maternally linked cohort files (years 1978-1997). Maternal body mass index was classified as Normal (18.5-24.9) (referent group), Obese (class 1, 30.0-34.9; class 2, 35.0-39.9; and extreme or class 3, 40 or more). Fetal growth phenotypes were defined as large for gestational age (LGA), appropriate for gestational age (AGA), and small for gestational age (SGA)...RESULTS: As compared with normal weight mothers, obese gravidas tended to program LGA infants at a higher and increasing rate with ascending obesity severity. The opposite effect was observed with respect to AGA and SGA programming patterns. Neonatal mortality among LGA infants was similar for obese (6.2 in 1,000) and normal (4.9 in 1,000) weight mothers (OR 1.05, 95% confidence interval [CI] 0.75-1.48) and regardless of obesity subtype. By contrast, SGA and AGA infants programmed by obese mothers experienced greater neonatal mortality as compared with those born to normal weight mothers (AGA OR 1.45, 95% CI 1.32-1.59; SGA OR 1.72, 95% CI 1.49-1.98)....

Results from Animal Models

Prog Biophys Mol Biol. 2011 Jul;106(1):307-14. doi: 10.1016/j.pbiomolbio.2010.12.004. Epub 2010 Dec 17. Periconceptional nutrition and the early programming of a life of obesity or adversity.
Zhang S, Rattanatray L, McMillen IC, Suter CM, Morrison JL. PMID: 21168433

...Whilst a short period of dietary restriction during the periconceptional period reverses the impact of periconceptional overnutrition on the programming of obesity, it also results in an increased lamb adrenal weight and cortisol stress response, together with changes in the epigenetic state of the insulin like growth factor 2 (IGF2) gene in the adrenal. Thus, not all of the effects of dietary restriction in overweight or obese mother in the periconceptional period may be beneficial in the longer term.

More blog entries from this blog on the topic of restricted prenatal weight gain:

• http://www.wellroundedmama.blogspot.com/search/label/weight%20gain%20in%20pregnancy
• http://www.wellroundedmama.blogspot.com/2011/10/restricting-prenatal-weight-gain-in.html
• http://www.wellroundedmama.blogspot.com/2010/12/fat-reserves-equal-extra-nutrition-on.html
• http://www.wellroundedmama.blogspot.com/2010/09/prenatal-weight-gain-when-conclusion-is.html
• http://www.wellroundedmama.blogspot.com/2010/10/prenatal-weight-gain-ignoring-possible.html
• http://www.wellroundedmama.blogspot.com/2010/10/prenatal-weight-gain-importance-of.html
• http://www.wellroundedmama.blogspot.com/2008/07/obesity-and-weight-gain-in-pregnancy.html
• http://www.wellroundedmama.blogspot.com/2008/07/obesity-and-weight-gain-in-pregnancy_19.html 
• http://www.wellroundedmama.blogspot.com/2008/07/obesity-and-weight-gain-in-pregnancy_21.html 
• http://www.wellroundedmama.blogspot.com/2008/10/little-historical-perspective-on-weight.html
• http://www.wellroundedmama.blogspot.com/2008/10/putting-baby-on-diet-before-its-even.html