Monday, October 6, 2008

A Little Historical Perspective on Weight Gain in Pregnancy

Preventing Pre-Eclampsia and Big Babies

Years ago, doctors regularly advised women to strictly limit their weight gain in pregnancy. They viewed this as a way to prevent pre-eclampsia (high blood pressure issues in pregnancy) because one of the symptoms of pre-eclampsia is a high weight gain from retaining fluids.

They decided that the large weight gain must be causing the pre-eclampsia, and therefore, preventing a large weight gain would help prevent pre-eclampsia.

They also wanted to prevent women from having large babies, so they strongly counseled women of all sizes to limit weight gain in order to get a smaller baby.

[Not only did they restrict weight gain, they also advised women to smoke to keep down their weight gain and fetal size, or to use diuretics to prevent fluid retention, both of which were later discovered to cause serious problems in pregnancy. Doh!]

All this was in the name of a worthy goal----preventing pre-eclampsia, which can be a very serious complication of pregnancy, and which is potentially deadly to both mother and baby. Their hearts were in the right place, but their methods were ill-considered and extreme.

Furthermore, the safety of this approach had not been established before it was adopted, as is unfortunately common in obstetrics. (Think of all the babies damaged when their mothers' doctors prescribed DES.)

Unforseen Consequences: Underweight Babies

What they found out later was that these extreme approaches actually CAUSED more harm then they averted. Many babies were born too small or very stressed; some no doubt died as a result of these interventions.

We also know that babies born underweight or "small-for-gestational age" (SGA) have more health problems later in life so the consequences of restricted fetal growth go far beyond problems at birth.

This is why the Institue of Medicine (IOM) adopted new weight gain guidelines in 1990, raising the recommended weight gains in pregnancy. They noted years of research that showed that low weight-gain in pregnancy caused an increase in SGA women of all sizes.

They also noted that in the 70s, when weight gain restrictions began easing up, there was a strong reduction in the occurrence of SGA babies.

So they raised the guidelines, and then began the big job of trying to get doctors to believe in this new system of weight gain guidelines. It was a difficult job.

Current IOM Weight Gain Guidelines

The old weight gain recommendations vary by source and by decade to some extent, but generally they fell somewhere between 10-20 lbs. By the 1970s, several organizations set a desirable range of around 20-25 lbs. or so.

The IOM raised these guidelines...but not across the board. They differentiated weight gain recommendations by BMI. Their guidelines were:

  • "Underweight" women: 28 - 40 lb. weight gain
  • "Normal" Weight women: 25 - 35 lb. weight gain
  • "Overweight" women: 15 - 25 lb. weight gain
  • "Obese" women: at least 15 lb. weight gain

The reason they had different weight goals by BMI was because weight gain's effect on fetal size varies by pre-pregnancy BMI.

The highest risk for SGA babies was in underweight women who didn't gain enough weight in pregnancy. Research clearly shows that gaining more weight can prevent many SGA babies in this group, so they raised the upper limit in this group to 40 lbs.

The effect of greater weight gain in preventing SGA babies is less pronounced as maternal size goes up; thus they felt that smaller gains were justifiable in the other groups. Still, women of "normal" size were now allowed to gain up to 35 lbs., which was a little more lenient than in the past.

The effect of weight gain on SGA babies is least strong in overweight and obese women, so therefore they felt only a small weight gain was appropriate in this group.

However, they did note that very small weight gains/losses caused increases in SGA babies across the board, even in obese women, and therefore they were not comfortable in recommending <15>This has been very controversial; many doctors still believed that obese women should gain little or nothing in pregnancy. They believed a larger gain in fat women would lead to a stronger risk of....ta da!!....pre-eclampsia. And big babies. And cesareans. And would result in more obesity after the pregnancy because of retained weight. So they've been chafing under these "guidelines" ever since.

Pressure to Revise the Weight Gain Guidelines

This chafing over guidelines has reached fever pitch now as a result of the obesity hysteridemic. More and more are pressing for lower weight gain goals.

Recently, a number of doctors have banded together to pressure the IOM to revise its guidelines on weight gain in pregnancy, and in particular to lower the guidelines for obese women.

They are hawking the same old concept again, namely: Large women have a higher risk for pre-eclampsia and big babies, so if we prevent a large weight gain in them, we'll lower the risk for pre-eclampsia and get smaller babies!! And prevent further obesity afterwards!!

Know what guidelines they are proposing for obese women?

  • Class I obese women (BMI 30-34.9): 10 - 25 lbs. gain
  • Class II obese women (BMI 35-39.9): 0 - 9 lbs. gain
  • Class III obese women (BMI >40): 0 - 9 lbs. loss
That's right, they are proposing that some fat women BE REQUIRED TO LOSE WEIGHT DURING PREGNANCY.

Alas, their P.R. campaign is working; the IOM has begun meetings to discuss revising weight gain guidelines again.

Coming Soon: Deconstructing the research being used to justify lowering these cutoffs.


MigiziNse-ikwe said...

When I was pregnant my doctor told me I could gain up to 40lbs before she would say anything. I put on roughly 35 and lost most of it after. Its' impossible to lose weight when your pregnant! What are these doctors thinking? Between the placenta, fluids, extra blood, bigger boobs and the actual weight of the baby-to-be how can you lose weight without harming yourself and the unborn child? This makes me sad.

Jo said...

All I can say is thank Maude for the midwives who, looking at my 5'-10", 215 lb. frame when I was two months pregnant, said "yeah, you should gain about 30 lbs. or so during your pregnancy", and followed it up with "we'll be checking your weight at every visit to make sure you're gaining enough, so that we'll know the baby is growing".

Lo and behold, that's just what I did. My last weight before the baby was born was 245.

Thanks for writing this.

Melissa said...

I find the obsession with weight gain during pregnancy kind of odd.
I really do believe that your genetics will pre-determine how much weight you gain.

I didn't eat that much different during pregnancy than before I was pregnant, and I was always active and I still gained 46 pounds.

I know women also who gained 70 pounds but most of it was water retention that they had no control over. After they had the baby it disappeared.

I think doctors need to monitor individuals and if they show signs of pre clampsia than deal with it. Stop whining about things to women before they even happen to them. From what I know about being pregnant when you put someone into a fear of something all to often that's what causes complications.

Like I've said before, women of all sizes can have preclampsia, so I don't think weight on it's own is a good enough indicator for the condition.

Rebekah Costello said...


Anonymous said...

I'm sure it's very healthy for the baby that mummy's on a strict diet to not only remain the same weight despite a growing baby and liquids and other stuff making her gain weight with pregnancy, but to also lose more weight to that during pregnancy she weighs less than she normally does. Yes, high intensity work-out and a starvation diet is veeery healthy, especially when pregnant!

I can only hope that most pregnant women know not to listen to doctors when they come with rubbish like that.

Cassie said...

This is terrifying to me. I am convinced that BMI is not representative of anything connected to health. My BMI is a point or two over the "normal" range, and I am sure that, were I in the normal range, I would be underweight and unhealthy.

To recommend so little weight gain, not to mention loss, just seems so obviously irresponsible. Is there a way to lobby the Institute of Medicine? Who is making these decisions? Who can influence them?

Anonymous said...

K, this is prolly gonna sound stupid, but how can a woman either gain 0lbs or lose weight during pregnancy and have a child? Cuz if a woman who is, say, 200lbs gets pregnant, she's gonna gain at least 5lbs of baby, right? Or do these weight gain guidelines count weight beyond baby weight. Cuz you can't really predict how big a baby will be until s/he's born, right? So, if a woman's aiming for 0 weight gain or even loss, wouldn't that increase the risk of miscarraige? This just makes no sense, man.

Anonymous said...


I have gone from 449 lbs to 429 lbs this pregnancy. I lost weight in both of my previous pregnancies as well (the first one I gained back 13 of the 20lbs lost in the last three months and the second I gained back 20 of the 45 lbs lost, most of which I lost to hyperemesis).

I am not on any restrictive diet...I just eat better and more often and more intuitively when pregnant than when not.

Basically, my adjusted and more conscious eating habits during my pregnancies as well as the child utilizing calories I intake just simply cause weight loss. I say again I am not trying to lose weight the amount of fast food cheese burgers I put away in the first few months can attest to that. I also don't think women should be forced to lose weight or put on a weight loss program while pregnant. I'm just illustrating how it can happen naturally and still result in healthy babies and mothers.

Anonymous said...

I'm 29 weeks pregnant right now and currently weigh 225, which is 15 lbs under my starting weight. But it's through no fault of my own. As you've mentioned before, some people do lose weight during pregnancy. But if I were trying to lose more, I can promose it wouldn't work. I lost the 15 lbs because of morning sickness, and then I've fluctuated up and down between -15 and -10 lbs for the last 2 months. My doctor congratulates me on eating healthier and being more active. That's not it at all. I think my body is at the weight it wants to be at right now. In fact, this is the weight I was when I delivered my first and second children (with the third I weighed a little more, but that baby was 12 days "late" and I put on a few more pounds in those last couple of weeks). I think this is the weight my body likes to be at when it's pregnant.

Unknown said...

It is essential to get your 80 grams of Protien dailey to avoid pre eclampsia. But instead, women vulnerable are told to diet, when what they really need to do is nutrient-up!