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Evidence Library · Staying well

Weight gain: what the guidelines say and what they predict

Associations, in both directions.

The 2009 National Academies ranges, still used in US care, are 28 to 40 pounds for underweight women, 25 to 35 for normal weight, 15 to 25 for overweight and 11 to 20 for obese.

In a meta-analysis of 23 studies and 1,309,136 women, 23% gained less than recommended and 47% gained more.

OutcomeGaining below the rangeGaining above the range
Small-for-gestational-age baby5 percentage points more3 points fewer
Large-for-gestational-age baby2 points fewer4 points more
Preterm birth5 points more2 points fewer
Cesarean deliveryNo significant difference4 points more
The part usually left outNearly half of women gain more than the range, and a quarter gain less, which means these categories describe most pregnancies rather than a minority. And these are associations, not proof that changing your weight gain changes the outcome. Weight in pregnancy is also one of the topics women most often report being spoken to badly about.
Where this comes from:
169. Rasmussen KM, Yaktine AL, editors. Weight gain during pregnancy: reexamining the guidelines. Washington, DC: National Academies Press; 2009.
170. Goldstein RF, Abell SK, Ranasinha S, Misso M, Boyle JA, Black MH, et al. Association of gestational weight gain with maternal and infant outcomes: a systematic review and meta-analysis. JAMA. 2017;317(21):2207-2225.

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