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How much weight gain in pregnancy is ok?

How much weight is healthy to gain in pregnancy depends on your BMI before pregnancy: roughly 12.5–18 kg if you started underweight, 11.5–16 kg at a normal weight, 7–11.5 kg if overweight, and 5–9 kg if you started with obesity.

Health Canada has adopted these BMI-based ranges from the US Institute of Medicine, and they are the standard used by Canadian care providers.

Strength of evidence

Strong

These ranges come from a national guideline (Health Canada, based on the IOM's 2009 evidence review) and are echoed by SOGC and ACOG committee guidance, plus a large individual-participant-data analysis pooling 36 randomized trials.

What the evidence says

There isn't one 'right' number for every pregnant person. The healthy amount of weight to gain depends on your body mass index, or BMI, before you got pregnant. BMI is a rough measure that compares your weight to your height.

Health Canada, following the same guidelines used across most of the world, suggests that women who started pregnancy underweight aim to gain about 12.5 to 18 kilograms (28 to 40 pounds). Those who started at a normal weight are advised to gain about 11.5 to 16 kilograms (25 to 35 pounds). If you started overweight, the suggested range is about 7 to 11.5 kilograms (15 to 25 pounds), and if you started with obesity, it's about 5 to 9 kilograms (11 to 20 pounds).

Most of this weight is not just fat. It includes the baby, the placenta, extra fluid, a larger uterus and breasts, and increased blood volume. Gaining too little has been linked to a higher chance of the baby being born small or early. Gaining too much has been linked to a higher chance of a large baby, a c-section, and to the mother keeping extra weight after birth.

The Canadian obstetricians' group (SOGC) has pointed out that for women with more severe obesity, these ranges may need individual adjustment, since some experts think even less weight gain might be reasonable in that group. This is still debated, so talk with your own care provider about what's right for you rather than picking a single number from a chart.

These targets are a general guide, not a strict rule. Every pregnancy is different, and your doctor or midwife can help you figure out what pace of weight gain is healthy for you and your baby, especially if you're expecting twins or have a health condition like gestational diabetes.

Sources

✓Reviewed by CH, MD, FRCPC

Reviewed by a specialist physician certified by the Royal College of Physicians and Surgeons of Canada, who has read this answer against the sources listed above and confirmed it reflects them. That is not medical advice about your child. How we review

Answer checked August 26, 2026

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