Recommended weight gain during pregnancy (IOM 2009)
| Pre-pregnancy BMI | Single baby | Twins |
|---|---|---|
| Underweight (<18.5) | 12.5–18.0 kg | 22.7–28.1 kg |
| Normal weight (18.5–24.9) | 11.5–16.0 kg | 16.8–24.5 kg |
| Overweight (25.0–29.9) | 7.0–11.5 kg | 14.1–22.7 kg |
| Obese (≥30.0) | 5.0–9.0 kg | 11.3–19.1 kg |
Weight gain in the first trimester is typically 0.5–2 kg total. The majority of weight gain occurs in the second and third trimesters.
How to use your results
These recommendations are from the Institute of Medicine (IOM) 2009 guidelines, the most widely used reference for pregnancy weight gain. Your healthcare provider may give slightly different advice based on your individual circumstances.
Weight gain during pregnancy includes: baby (~3–3.5 kg), placenta (~0.7 kg), amniotic fluid (~0.8 kg), increased blood volume (~1.5 kg), breast tissue (~0.5–1 kg), uterus (~1 kg), and maternal fat stores (~2–4 kg).
Frequently asked questions
How much weight should I gain during pregnancy?
Depends on your pre-pregnancy BMI. Normal weight women (BMI 18.5–24.9): 11.5–16 kg. Underweight: 12.5–18 kg. Overweight: 7–11.5 kg. Obese: 5–9 kg. Twins: add 4–6 kg to single-baby recommendations.
Is it normal to lose weight in the first trimester?
Yes — nausea and vomiting often cause weight loss or no gain in the first trimester. This is normal for many pregnancies. Most weight gain occurs in the 2nd and 3rd trimesters.
Can I diet during pregnancy?
Do not intentionally diet or restrict calories during pregnancy. Even overweight women should gain the recommended amount. Insufficient weight gain is associated with low birth weight and preterm birth. Focus on nutrient-dense foods rather than calorie restriction.
How many extra calories do I need during pregnancy?
First trimester: no additional calories needed. Second trimester: approximately 340 extra kcal/day. Third trimester: approximately 450 extra kcal/day. These are rough averages — individual needs vary.
Is it dangerous to gain too much weight during pregnancy?
Excessive weight gain increases risks of: gestational diabetes, high blood pressure, C-section delivery, and difficulty losing weight postpartum. However, inadequate weight gain also carries risks. Aim within the recommended range.
When do I gain the most weight during pregnancy?
Most weight gain occurs in the 2nd and 3rd trimesters, at approximately 0.3–0.5 kg per week. The first trimester typically involves minimal total gain (0.5–2 kg). Weekly gain accelerates slightly in the third trimester.
Will I lose the pregnancy weight after birth?
Most women lose 4–6 kg immediately after delivery (baby, placenta, fluid). Breastfeeding can help with additional weight loss. Most pregnancy weight is lost within 6–12 months postpartum with healthy diet and activity.
How does pregnancy affect my calorie needs?
Calorie needs increase modestly — approximately 340 kcal/day in the 2nd trimester and 450 kcal/day in the 3rd. Quality of calories matters more than quantity. Focus on protein, folate, iron, calcium and omega-3s.