What Does the Research Say About Weight Gain During Pregnancy?

I am pregnant with my second child and was recently told by my provider at 34 weeks that I need to slow down my weight gain for the remainder of my pregnancy. At that appointment, I had gained 43 pounds since the beginning of my pregnancy, which is a similar amount of weight gained during my first pregnancy. For context, I started this pregnancy with a BMI of 24 and my prior pregnancy with a BMI of 26. However, during my first pregnancy, in the height of COVID in NYC, I wasn’t exercising regularly and we were stress-eating takeout five days/week. Fast-forward to today, and I work out five days/week with a personal trainer doing a combination of cardio and strength training, and I generally follow a low-glycemic diet. Furthermore, my weight gain in my first pregnancy did not translate to weight on the baby — my son was born at 7 lbs. 4 oz. When I shared this with my doctor, she noted that appropriate weight gain was 25-30 lbs. and was still adamant I increase my cardio exercise and restrict my diet further. What does the research tell us about weight gain during pregnancy? How can it be that every woman should generally gain the same amount of weight based on their starting weight?

—Weighted Down over Weight Gain

First of all, let me just say this makes me angry. I’m sorry you are having this experience. In some ways, I had a similar experience in my first pregnancy — I wrote about it in Expecting Better — and it remains one of the main motivating experiences behind that book.

Recommendations for weight gain are based on starting weight, loosely, and the 25-to-30-pound recommended weight gain is for people who start at a BMI between 18 and 25. However: it’s hard to consider these recommendations without asking why they are introduced. The concern with gaining “too much” weight in pregnancy is a large baby, which can increase the risk of some birth complications. These effects, though, are quite small and vary considerably across people. There isn’t anything in the data that would suggest that if you go over the “magic” 25-to-30-pound figure, there is something immediately bad that happens.

What is more frustrating about your story and your interaction here is that the advice seems to completely ignore a tremendous amount of individual-specific information. You gained a similar amount of weight in the last pregnancy, and your baby was right in the middle of the typical infant weight range. You’re already exercising, which, I have argued elsewhere, has a lot more evidence-based links to health than weight alone. The tenor of the interactions you describe seem focused only on some arbitrary weight number, rather than thinking holistically about the health of you and your pregnancy.

There is much more that can be said here — and I will note that you’re experiencing this from the perspective of a thin person, and others have written about the even deeper issues that arise for patients who are in larger bodies. But in the end, for you, I’m not sure there is much to do but try to ignore it or find a new provider who makes you feel comfortable. I dislike saying that, since the doctor-patient relationship is so important and it would be so much better if you could get to a place of understanding, but I’m not optimistic.