Recommended Weekly Weight Gain During Second and Third Trimesters
Normal-weight women should gain 0.5-0.9 kg (approximately 1-2 pounds) per week during the second and third trimesters. 1
Weight Gain Recommendations by Pre-Pregnancy BMI
The weekly weight gain targets during the second and third trimesters vary based on a woman's pre-pregnancy body mass index (BMI):
Normal-Weight Women (BMI 18.5-24.9)
- Gain 0.5-0.9 kg per week throughout the second and third trimesters 1, 2
- Total pregnancy weight gain should be 1.4-2.3 kg in the first trimester, followed by this weekly rate for the remainder of pregnancy 1
Underweight Women (BMI <19.8)
- Gain 0.5-0.9 kg per week during the second and third trimesters 2
- Should aim for a total pregnancy weight gain of up to 18 kg (40 lbs) 1, 2
- First trimester target: 1.4-2.3 kg 2
Overweight Women (BMI 25-29.9)
- Gain at less than 50% of the rate recommended for normal-weight women 2
- This translates to approximately 0.25-0.45 kg per week during the second and third trimesters 2
Obese Women (BMI >30)
- Gain minimally during the second and third trimesters 1, 2
- Total pregnancy weight gain should be limited to 5.0-9.1 kg (11-20 lbs) for the entire pregnancy 1
- One guideline suggests a relatively small total gain of 7 kg 2
Supporting Nutritional Requirements
To support appropriate weight gain during the second and third trimesters:
- Add 300 kcal/day to baseline energy needs (no additional calories are needed in the first trimester unless the woman has depleted body reserves) 1, 3
- Protein intake should be 0.75 g/kg/day plus an additional 10 g/day 1, 3
- Iron supplementation (30 mg/day) is recommended during the second and third trimesters 1, 2
Clinical Considerations and Common Pitfalls
Provider counseling is critical but often inadequate. Only 52% of women report receiving provider advice on weight gain during pregnancy, yet provider recommendations significantly influence women's intended weight gain 4. When providers do give advice, 79% cite recommendations within guidelines, but 11% recommend excessive weight gain and 9% recommend insufficient gain 4.
Excessive weight gain is common, particularly in overweight and obese women. Approximately 60% of pregnant women do not comply with current weight gain recommendations, with overweight and obese women most likely to exceed targets 5. This is concerning because excessive gestational weight gain is associated with gestational diabetes, pre-eclampsia, macrosomia, increased cesarean delivery risk, and postpartum weight retention 6.
Insufficient weight gain affects approximately 20% of pregnant women and increases risks of preterm birth and difficulties establishing breastfeeding 2. Birth weight correlates significantly with maternal BMI, total weight gain, and gestational age 5.
Avoid hypocaloric diets below 1,200 calories per day as they result in ketonemia and ketonuria 1, 3. Weight management should focus on appropriate caloric intake and balanced nutrition rather than restriction 1.
Initiate weight gain discussions early and repeatedly. Women prefer that healthcare providers initiate conversations about gestational weight gain goals and value one-on-one discussions throughout pregnancy 7. Women view their clinicians as the most reliable source of information and are open to visual aids showing their own weight gain progression 7.