Recommended weight gain by BMI
The most widely used guidelines come from the US Institute of Medicine (IOM, 2009). They are based on your body mass index (BMI) before pregnancy:
| Pre-pregnancy BMI | Total gain (single baby) | Weekly gain, 2nd & 3rd trimester | Total gain (twins) |
|---|---|---|---|
| Underweight (<18.5) | 12.5–18 kg | 0.44–0.58 kg | No guideline |
| Normal (18.5–24.9) | 11.5–16 kg | 0.35–0.50 kg | 17–25 kg |
| Overweight (25–29.9) | 7–11.5 kg | 0.23–0.33 kg | 14–23 kg |
| Obese (≥30) | 5–9 kg | 0.17–0.27 kg | 11–19 kg |
Weight gain in the first trimester is small – usually 0.5–2 kg – and some women lose a little because of nausea. Most gain happens after week 13.
Where does the weight go?
For a woman gaining around 12.5 kg, only about a quarter of it is the baby. The rest supports the pregnancy:
| Component | Approximate weight at term |
|---|---|
| Baby | 3–3.5 kg |
| Placenta | 0.6–0.7 kg |
| Amniotic fluid | 0.8–1 kg |
| Larger uterus | 0.9–1 kg |
| Breast tissue | 0.4–0.5 kg |
| Extra blood volume | 1.2–1.5 kg |
| Extra fluid in tissues | 1.2–1.7 kg |
| Maternal fat stores | 3–4 kg |
A note on BMI for Indian women
South Asian adults tend to have more body fat and higher metabolic risk at the same BMI than European adults. For this reason, Indian guidelines often treat a BMI of 23–24.9 as overweight and 25 or more as obese. The calculator uses the international IOM categories, but flags when your BMI falls in the 23–24.9 range so you can discuss a target with your doctor.
Eating for two? Not quite
You need no extra calories in the first trimester, roughly 350 extra kcal a day in the second trimester and about 450 extra kcal in the third – the equivalent of a bowl of dal with a roti and a glass of milk, not a second full meal. Focus on protein (dal, paneer, curd, eggs, fish, soy), iron-rich foods (green leafy vegetables, jaggery, dates, meat) and calcium.
When weight gain needs attention
- Gaining more than about 1 kg in a single week in the second half of pregnancy, especially with swelling of the face or hands – this can signal pre-eclampsia.
- No weight gain, or weight loss, over several weeks in the second or third trimester.
- Persistent vomiting that stops you keeping food or fluids down (hyperemesis gravidarum).
Frequently asked questions
How much weight should I gain in pregnancy?
For a single baby, 11.5–16 kg if your BMI was normal before pregnancy; 12.5–18 kg if underweight; 7–11.5 kg if overweight; and 5–9 kg if obese.
How much weight should I gain in the first trimester?
Usually only 0.5–2 kg. Many women with morning sickness gain nothing or lose a little, which is generally fine if it recovers in the second trimester.
Is it safe to lose weight during pregnancy?
Deliberate dieting to lose weight is not recommended during pregnancy. Women with obesity may be advised to gain less, but only under medical supervision.
How much weight should I gain with twins?
For a normal pre-pregnancy BMI, 17–25 kg. Your doctor may monitor your gain more closely because twin pregnancies have higher nutritional demands.
Does breastfeeding help lose pregnancy weight?
Breastfeeding uses around 500 kcal a day and can help, but postpartum weight loss varies. Most women return close to their pre-pregnancy weight within 6–12 months.
Medical disclaimer: The results and information on this page are estimates for general education only. They are not a diagnosis and do not replace advice from your gynaecologist, obstetrician or midwife. If you have pain, bleeding, reduced baby movements or feel unwell, contact your doctor or call 108 immediately. Read the full disclaimer.
Sources & further reading
- Institute of Medicine & National Research Council. Weight Gain During Pregnancy: Reexamining the Guidelines (2009). National Academies Press.
- WHO Expert Consultation. Appropriate body-mass index for Asian populations. Lancet 2004;363:157–63.
- Ministry of Health & Family Welfare, Government of India. Maternal health guidelines, PMSMA and Anemia Mukt Bharat. nhm.gov.in
- World Health Organization. WHO recommendations on antenatal care for a positive pregnancy experience (2016). who.int