Thursday, August 18, 2016

"Safe" Gestational Weight Loss?

Graphic from this misleading article. The article addresses
improving diet and exercise in pregnancy but doesn't mention any
of the studies that show risks associated with weight loss in pregnancy
While researching another post, I was angered to see that some providers ─ and media outlets ─ are still worshiping at the altar of weight loss in pregnancy for "obese" pregnant women.

Augh! I can't believe this is still being promoted, even after a number of studies suggesting there are risks to gestational weight loss.

I know, I know. Many care providers hope weight loss in pregnancy is the magical pill to automatically improve pregnancy outcomes in women of size and leave them forever skinnier afterwards. They see it as a theoretical win-win. But it just doesn't happen this way ─ and it is associated with significant risks. That is not a win-win situation.

Too many authors extol the possible benefits of gestational weight loss (GWL) while significantly downplaying or completely ignoring the possible risks.

I find this incredibly frustrating and irresponsible.

Ignoring the Evidence for Harm

In the article accompanying the graphic above, for example, the author never addresses the potential risks of losing weight during pregnancy. A fair and balanced article ought to look at both benefits and risks, but it doesn't.

The article suggests improving diet and exercise in pregnancy and notes some potential benefits from that. I don't have a problem with promoting good habits and agree that sometimes this may prevent certain complications, but the article makes the typical biased assumption that all fat women have terrible habits. This promotes the stereotype of the gluttonous obese person, which just doesn't match the life experience of the many fat people who have normal habits. So the article is problematic already for its automatic assumptions.

More importantly, the author never mentions any of the studies which have found risks associated with gestational weight loss. This is intellectually dishonest and shows an obvious agenda. The author implies that it's perfectly safe to lose weight in pregnancy, even though the issue of safety was not actually addressed in the article.

So what does the research say?

Over and over again, researchers have found that weight loss in pregnancy is associated with too-small babies and possibly prematurity.

In one study highlighted below, for example, "overweight" and "obese" women who had been diagnosed with gestational diabetes were enrolled in the California Diabetes and Pregnancy Program. Those who lost weight were compared with those who did not. 

The authors found that gestational weight loss was associated with some problematic outcomes, including more Small-for-Gestational-Age (SGA) babies and more premature babies. But this study is not the only one to find risks with Gestational Weight Loss (GWL). Here are a few more that have also found problems:
  • Bodnar 2010 - GWL increased risk for SGA and preterm births among obese women
  • Bayerlein 2011 - GWL increased risk for SGA and preterm births in all but class III obese women
  • Blomberg 2011 - GWL increased risk for SGA even among class III obese women
  • Catalano 2014 - GWL more than doubled the risk for SGA among obese women
  • Cox Bauer 2016 - GWL doubled the risk for low birth weight babies
As a result, one recent meta-analysis concluded:
GWL should not be advocated in general for obese women.
Yet there are still far too many doctors, midwives, and media articles promoting just that.

An Acceptable Trade-Off of Risks?

Critics will point out that gestational weight loss has benefits that off-set the increased risk of SGA and prematurity. For example, in the California Diabetes and Pregnancy Program study above, women who lost weight during the study experienced decreased risks for a big baby (macrosomia or LGA), cesarean sections, and NICU (Neonatal Intensive Care Unit) admission. The authors felt that this trade-off was good enough reason to promote continued inquiry into gestational weight loss, despite the increased risks for SGA and premature babies.

But these arguments have a huge fault in them ─ ignoring iatrogenic (physician-caused) variables. For example, when doctors see a large woman with a larger weight gain, they fear macrosomia and shoulder dystocia. As a result, they may disproportionately induce those who gained more weight and have a low surgical threshold for cesareans in this group. Thus, a higher cesarean rate in this group be more a reflection of their doctors' fears and intervention levels rather than an actual causal effect a larger gain.

Furthermore, a higher induction rate could also explain increased NICU admissions in this group, since induction places increased stress on the baby. Also, bigger babies receive more surveillance for possible low blood sugar, which often entails a trip to the NICU. So while the increased NICU admissions in the weight gain group cannot be dismissed, it may also simply be a surrogate marker for increased interventions in this group.

Only fetal size is directly linked to weight gain in pregnancy. Very high gains lead to bigger babies on average, and avoiding very high gains is probably a good idea. However, that doesn't mean that pressuring women to lose weight in pregnancy is better.

SGA has serious potential consequences, yet this is shrugged off as being fairly unimportant by many researchers. They feel it is worth the trade-off for fewer big babies. Culturally, big babies are the ultimate "boogeyman" in the obstetric world these days because OBs are often sued for birth injuries caused by shoulder dystocia. Yet drugging women, forcing them to birth on their backs in immobile positions, and rushing the baby out too quickly have a lot to do with shoulder dystocia and birth injuries. How sad that doctors would rather risk more SGA babies than learn how to deal more effectively with big babies.

I am alarmed at the number of care providers and researchers who consider SGA and prematurity a "minor" matter and a worthwhile trade-off.

SGA and prematurity are significant concerns for babies because they are at increased risk for fetal death, sudden infant deathcognitive delay, and poor neurodevelopmental outcomes.

SGA babies also tend to have more significant downstream health effects like metabolic disease, including insulin resistance, diabetesmetabolic syndrome, and cardiovascular disease. SGA and growth-restricted babies face life-long health risks.

It doesn't end there. SGA babies are clearly at increased risk for stillbirth. And there is now research shows that SGA babies of obese women are at particular risk for stillbirth. Stillbirth!

Additionally, recent research shows that obese women with gestational weight loss had higher risks of infant death after birth.

Yes, macrosomia has risks too, like higher rates of shoulder dystocia and birth injuries, and possibly higher cesarean rates.

However, some research suggests that SGA babies are worse off than LGA babies. And having a bigger baby on average may be nature's way of protecting the babies of high-BMI women, since stillbirth risks are lower among LGA babies than among SGA or average-sized babies in obese women.

Personally, if I had to choose, I'd rather gain a little more weight and risk a bigger baby than to lose weight and risk an unhealthily-small baby, putting it at risk for possible stillbirth or life-long health problems.

Yet researchers continue to shrug off SGA as a minor thing. The author of one study on limiting weight gain in obese women said, "What conclusions you draw depends on how you value the adverse effects." In other words, is a decrease in cesareans and big babies worth an increase in unhealthily-small babies?

I say NO. SGA babies need to be taken far more seriously as a downside to very low weight gains and weight loss in pregnancy, even if the price is a few more big babies or possibly even a few cesareans.

Or better yet, care providers could learn how to attend the birth of a big baby more safely.

The best route to improve outcome may be to address fears and intervention levels around big babies rather than to make all fat women lose weight in pregnancy and risk too-small babies.

Take-Away Messages

Messages like this are irresponsible and need to stop
Websites that promote weight loss during pregnancy still abound in the media, and articles are still being published that say that weight loss in pregnancy is "safe" (I refuse to link to them).

And some doctors are still advising overweight and obese women to lose weight during pregnancy. Dr. Thomas Myles, a professor of obstetrics and gynecology at Saint Louis University School of Medicine, said in one article, "I usually tell my [obese] patients that gaining less than 10 pounds and even losing up to 10 pounds is appropriate."

Doctors and the media need to stop promoting weight loss in pregnancy for obese women. 

We've talked about this extensively before but despite the studies showing risks, the media and many providers keep promoting it. This is potentially dangerous.
Yes, some women of size naturally lose weight in pregnancy or gain very little. As long as they are not restricting calories to lose weight, have good overall nutrition, and their babies show normal growth curves, their outcomes are usually fine. I'm not worried about women who lose a little weight incidentally. Sometimes that happens in larger women and it's not a big deal.

Nor am I worried about care providers encouraging good basic nutrition principles and regular exercise in women (although I think they should do that for all women and not just fat women). Good nutrition is a basic and ALL pregnant women should be encouraged to work on it, though I would challenge providers to find a way to talk to their clients about nutrition and weight gain without condescension, moralizing, and automatic assumptions.

What I am deeply worried about is encouragement for women of size to intentionally lose weight in pregnancy, and the dangerous nutritional advice that is being given to some obese women in order to promote this dubious goal. 

For example, one doctor told his patient to "lose 1-2 lbs/week for the remaining 7 weeks of pregnancy...He suggests 1000 calories/day and 1 hour of heavy cardio exercise." Others have been told that they should lose 40 lbs. while pregnant, or that the baby will get all it needs from fat reserves so it's okay to lose weight. A few care providers are telling obese women to cut out entire food groups ("never eat carbs" or "cut out all fruit"), to go on SlimFast shakes, or to "eat nothing but vegetables" in order to limit weight gain.

Although most doctors are not this extreme, some women are being pressured into some dangerous nutritional stuff, all in the name of gestational weight loss. And women are being pressured into more interventions (like unnecessary inductions and planned cesareans) if they gain above what their care providers think they "should" be gaining.

Researchers MUST start recognizing the fact that their well-intentioned studies on restricted weight gain in obese women are, in practice, resulting in very harmful dietary advice and punitive practices for women who gain "too much."

Promoting gestational weight loss may be doing FAR more harm than good in obese women, especially those in borderline BMI categories for whom GWL is particularly risky. But even in "morbidly obese" women, there is enough evidence of possible harm that care providers should not be pushing for intentional weight loss in pregnancy.  

Instead, I urge care providers to focus on:
  • Reasonable nutrition
  • Regular exercise
  • Proactive care protocols 
In addition, caregivers MUST start looking at their own practice patterns in response to obese mothers' weight gain (especially induction for big baby) and how this impacts cesarean rates, NICU admissions, and morbidity in high-BMI women and their infants.

Here's what I want researchers and media to change:
  1. Stop promoting weight loss in pregnancy for obese women 
  2. Stop trying to sell gestational weight loss as "perfectly safe" and acknowledge the research that shows significant risks with it 
  3. Start recognizing that providers' responses to obese women's weight gain impacts outcomes, perhaps more than the gain itself
  4. Learn how to attend the births of big babies more safely 
Stop focusing so exclusively on the scale and start focusing on reasonable habits and reducing interventions as ways to improve outcomes in high-BMI women.


Obesity (Silver Spring). 2013 Apr 24. doi: 10.1002/oby.20490. [Epub ahead of print] Gestational weight loss and perinatal outcomes in overweight and obese women subsequent to diagnosis of gestational diabetes mellitus. Yee LM, Cheng YW, Inturrisi M, Caughey AB.  PMID: 23613187
OBJECTIVE: To investigate whether gestational weight loss after the diagnosis of gestational diabetes mellitus (GDM) in overweight and obese women is associated with improved perinatal outcomes...METHODS: Retrospective cohort study of 26,205 overweight and obese gestational diabetic women enrolled in the California Diabetes and Pregnancy Program. Women with gestational weight loss (GWL) during program enrollment were compared to those with weight gain...RESULTS: 5.2% of women experienced GWL. GWL was associated with decreased odds of macrosomia (aOR 0.63, 95% CI 0.52-0.77), NICU admission (aOR 0.51, 95% CI 0.27-0.95), and cesarean delivery (aOR 0.81, 95% CI 0.68-0.97). Odds of SGA status (aOR 1.69, 95% CI 1.32-2.17) and preterm delivery <34 weeks (aOR 1.71, 95% CI 1.23-2.37) were increased.  CONCLUSIONS: In overweight and obese women with GDM, third trimester weight loss is associated with some improved maternal and neonatal outcomes, although this effect is lessened by increased odds of SGA status and preterm delivery. We recommend further research on weight loss and interventions to improve adherence to weight guidelines in this population.
BJOG. 2011 Jan;118(1):55-61. doi: 10.1111/j.1471-0528.2010.02761.x. Epub 2010 Nov 4. Associations of gestational weight loss with birth-related outcome: a retrospective cohort study. Beyerlein A1, Schiessl B, Lack N, von Kries R. PMID: 21054761
...DESIGN: Retrospective cohort study. 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...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. doi: 10.1097/AOG.0b013e318214f1d1. Maternal and neonatal outcomes among obese women with weight gain below the new Institute of Medicine recommendations. Blomberg M1. 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....
Obes Rev. 2015 Mar;16(3):189-206. doi: 10.1111/obr.12238. Epub 2015 Jan 18. Can we safely recommend gestational weight gain below the 2009 guidelines in obese women? A systematic review and meta-analysis. Kapadia MZ1, Park CK, Beyene J, Giglia L, Maxwell C, McDonald SD. PMID: 25598037
A systematic review was conducted to determine the risk of adverse pregnancy outcomes with gestational weight gain (GWG) below the 2009 Institute of Medicine guidelines compared with within the guidelines in obese women. MEDLINE, Embase, Cochrane Register, CINHAL and Web of Science were searched from 1 January 2009 to 31 July 2014. Quality was assessed using a modified Newcastle-Ottawa scale. Three primary outcomes were included: preterm birth, small for gestational age (SGA) and large for gestational age (LGA). Eighteen cohort studies were included. GWG below the guidelines had higher odds of preterm birth (adjusted odds ratio [AOR] 1.46; 95% confidence interval [CI] 1.07-2.00) and SGA (AOR 1.24; 95% CI 1.13-1.36) and lower odds of LGA (AOR 0.77; 95% CI 0.73-0.81) than GWG within the guidelines. Across the three obesity classes, the odds of SGA and LGA did not show any notable gradient and remained unexplored for preterm birth. Decreased odds were noted for macrosomia (AOR 0.64; 95% CI 0.54-0.77), gestational hypertension (AOR, 0.70; 95% CI 0.53-0.93), pre-eclampsia (AOR 0.90; 95% CI 0.82-0.99) and caesarean (AOR 0.87; 95% CI 0.82-0.92). GWG below the guidelines cannot be routinely recommended but might occasionally be individualized for certain women, with caution, taking into account other known risk factors.
Increased Risks for SGA Infants of Obese Women

J Matern Fetal Neonatal Med. 2016 Jul 22:1-17. [Epub ahead of print] The effects of maternal obesity on perinatal outcomes among those born small for gestational age. Yao R1, Park BY2, Caughey AB3. PMID: 27450769
BACKGROUND:...Small for gestational age (SGA) neonates born to obese women may be associated with pathological growth with increased neonatal complications. METHODS: This was a retrospective cohort study of all non-anomalous singleton neonates born in Texas from 2006-2011. Analyses were limited to births between 34 and 42 weeks gestation with birth weight ≤10th percentile. Results were stratified by maternal pre-pregnancy BMI class. The risk for stillbirth, neonatal death, neonatal intensive care unit (NICU) admission and 5 minute Apgar scores <7 were estimated for each obesity class and compared to the normal weight group. Multivariable logistic regression analyses were performed to control for potential confounding variables. RESULTS: The rate of stillbirth was 1.4/1,000 births for normal weight women, and 2.9/1,000 among obese women (p < 0.001, aOR: 1.83 [1.43, 2.34]). The rate of neonatal deaths among normal weight women was 4.3/1,000 births, whereas among obese women it was 4.7/1,000 (p = 0.94, aOR: 1.10 [0.92, 1.30]). A dose-dependent relationship between maternal obesity and stillbirths was seen, but not for other neonatal outcomes. CONCLUSION: Among SGA neonates, maternal pre-pregnancy obesity was associated with increased risks for stillbirth, NICU admission and low Apgar scores but not neonatal death.
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 HM1, 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)...Fetal growth phenotypes were defined as large for gestational age (LGA), appropriate for gestational age (AGA), and small for gestational age (SGA)...RESULTS:..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). CONCLUSION: Compared with normal weight mothers, obese women are least successful at programming SGA, less successful at programming AGA, and equally as successful at programming LGA infants.
BJOG. 2016 Feb 8. doi: 10.1111/1471-0528.13896. [Epub ahead of print] Comparison of methods for identifying small-for-gestational-age infants at risk of perinatal mortality among obese mothers: a hospital-based cohort study. Hinkle SN1, Sjaarda LA1, Albert PS2, Mendola P1, Grantz KL1. PMID: 26853429
OBJECTIVE: To assess differences in small-for-gestational age (SGA) classifications for the detection of neonates with increased perinatal mortality risk among obese women and subsequently assess the association between prepregnancy body mass index (BMI) status and SGA. DESIGN: Hospital-based cohort. SETTING: Twelve US clinical centres (2002-08). POPULATION: A total of 114 626 singleton, nonanomalous pregnancies. ...RESULTS: The overall perinatal mortality prevalence was 0.55% and this increased significantly with increasing BMI (P < 0.01)...SGA is less common among obese women but these SGA babies are at a high risk of death and remain an important group for surveillance.

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