Weight Gain in Pregnancy: What the Ranges Mean

Weight Gain in pregnancy: how to think about it

ACOG guidance sets recommended weight gain by pre-pregnancy body mass index rather than as a single figure, because the appropriate amount differs with starting weight. The commonly cited ranges for a single pregnancy are roughly 28 to 40 pounds for a BMI under 18.5, 25 to 35 pounds for a BMI of 18.5 to 24.9, 15 to 25 pounds for a BMI of 25 to 29.9, and 11 to 20 pounds for a BMI of 30 or above. Twins carry different ranges. The reasoning behind having ranges at all is that both ends carry associations: too little gain is linked with low birth weight and preterm birth, while gain well above the range is linked with a larger baby, more caesarean births and more weight retained afterwards. Most of the gain is expected in the second and third trimesters. Because so much of the number is fluid, placenta and blood volume rather than fat, weekly fluctuations are normal and the pattern matters more than any single reading.

Weight Gain: safer choices

• Discussing your own range with your midwife or doctor, since ACOG ties the recommendation to pre-pregnancy BMI rather than giving one figure.
• Expecting most gain in the second and third trimesters. Very little is expected in the first, and some people lose weight early with nausea.
• Focusing on eating well rather than on the number, including the folic acid and vitamin D that pregnancy guidance recommends.
• Staying gently active, which ACOG recommends at about 150 minutes a week of moderate activity for uncomplicated pregnancies.
• Raising it with your team if you gain very rapidly or lose weight, so the cause can be looked at rather than guessed.

Weight Gain: what to avoid or double-check

• Do not diet to restrict weight gain in pregnancy without clinical supervision. Pregnancy is not the time for intentional weight loss unless a clinician is guiding it.
• Avoid treating the ranges as pass or fail. They are population guides, and individual pregnancies vary for reasons that have nothing to do with eating.
• Do not ignore sudden swelling with rapid weight gain, particularly after 20 weeks with headache or visual changes, which needs same-day review for pre-eclampsia.
• Avoid weight-loss supplements and appetite suppressants entirely in pregnancy.

How SafeMama helps

SafeMama focuses on product labels rather than scales, but it can check the things people take around this topic, including prenatal vitamins, protein powders, meal replacements and any supplement marketed for weight, several of which are not suitable in pregnancy.

Open the SafeMama app, scan the barcode or search the ingredient, then use the result as a starting point for a conversation with your healthcare provider.

Sources

• ACOG how much weight should I gain during pregnancy
• ACOG nutrition during pregnancy
• ACOG exercise during pregnancy