How much weight should I gain during pregnancy?

It depends on your pre-pregnancy BMI: 11.5–16 kg (25–35 lb) for a normal BMI, more if you started underweight, less if overweight or obese.

Is gaining too little a problem?

Too little gain is linked to low birth weight and preterm birth. If you are below the recommended range, talk to your provider about nutrition.

What if I gain too much?

Excess gain raises the risk of gestational diabetes, high blood pressure, cesarean delivery and difficulty losing weight later. Prenatal care helps keep a healthy pace.

Do these ranges apply to twins?

No. Twin pregnancies have higher recommended gains. These ranges are for a single baby.

Pregnancy & Baby

Pregnancy Weight Gain Calculator

How much weight is healthy to gain in pregnancy depends on where you started: someone who begins underweight can gain more, and someone with a higher BMI should gain less. Enter your pre-pregnancy weight and height for the IOM range.

Your numbers

Result

Recommended gain (min)

11.5

Recommended gain (max)

Expected gain so far: 2.9–5.5 kg
Pre-pregnancy category: Normal weight

Recommended total gain by pre-pregnancy BMI (IOM 2009)
Category	BMI before pregnancy	Recommended gain
Underweight	below 18.5	12.5–18 kg (28–40 lb)
Normal weight	18.5–24.9	11.5–16 kg (25–35 lb)
Overweight	25–29.9	7–11.5 kg (15–25 lb)
Obese	30 or more	5–9 kg (11–20 lb)

How much to gain depends on starting BMI

The Institute of Medicine (IOM, 2009) ranges tie total gain to your BMI before pregnancy: underweight 12.5–18 kg (28–40 lb), normal 11.5–16 kg (25–35 lb), overweight 7–11.5 kg (15–25 lb), obese 5–9 kg (11–20 lb). The goal is enough reserve for the baby without excess that raises risks like gestational diabetes and pre-eclampsia.

How the gain is spread out

In the first trimester the gain is small — about 0.5 to 2 kg total. From around week 14 it rises more steadily, at a weekly pace that depends on your band (roughly 0.17 kg/week if obese up to 0.58 kg/week if underweight). That is why the "so far" estimate combines the first trimester with the pace of the weeks after it.

Twins and special cases

These ranges are for a single pregnancy. For twins, the recommended gain is higher (for example 17–25 kg at a normal BMI). Teenagers, short stature and certain health conditions also change the target. This is an educational guide — your prenatal provider is who tracks and adjusts your actual gain.

Informational and educational result. Not a substitute for professional advice.

Frequently asked questions

Sources

Institute of Medicine (IOM, 2009) — Weight Gain During Pregnancy

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