Pregnancy Weight Gain Calculator (IOM Guidelines)
Find how much weight to gain in pregnancy from your BMI before pregnancy, week by week, with the IOM guidelines for one baby or twins.
Recommended gain week by week
| Week | Minimum | Maximum |
|---|
These are general guidelines from the Institute of Medicine (2009). Your doctor or midwife may set a different target for you.
What it does
The calculator uses the guidelines of the US Institute of Medicine (IOM, 2009), also followed by the CDC and by obstetricians' associations. The recommended total gain depends on the body mass index (BMI) before pregnancy: 12.5 to 18 kg for underweight, 11.5 to 16 kg for normal weight, 7 to 11.5 kg for overweight and 5 to 9 kg for obesity. In the first trimester the gain is small, 0.5 to 2 kg in total; after that it follows a steady weekly rate until birth.
How to use it
- Choose metric or imperial units and type your height and your weight before pregnancy.
- Optionally type the current week and your weight today to compare with the recommended range.
- See the total range, the weekly rate and the table week by week. Tick twins for the twin ranges.
The arithmetic runs in your browser. Nothing you type is sent anywhere and nothing is stored, so you can use these with real numbers.
Frequently asked questions
How much weight should I gain during pregnancy?
It depends on your BMI before pregnancy. With a normal BMI (18.5 to 24.9) the IOM recommends 11.5 to 16 kg (25 to 35 lb). A woman 1.65 m tall who weighed 60 kg (BMI 22.0) would end pregnancy at 71.5 to 76 kg.
How much weight should I have gained by 20 weeks?
With a normal BMI, about 3.4 to 5.6 kg (7 to 12 lb): 0.5 to 2 kg in the first trimester and then a steady gain until the total at 40 weeks.
How much weight should I gain with twins?
The IOM provisional guidelines for twins are 17 to 25 kg (37 to 54 lb) with a normal BMI, 14 to 23 kg (31 to 50 lb) if overweight and 11 to 19 kg (25 to 42 lb) with obesity. There is not enough data for underweight women.
Is it safe to lose weight during pregnancy?
Dieting to lose weight is not recommended in pregnancy. With a BMI of 30 or more the IOM range is 5 to 9 kg (11 to 20 lb); a lower gain should only be planned with your doctor.
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Institute of Medicine (2009) — Weight Gain During Pregnancy
CDC — Weight Gain During Pregnancy