Recommended Weight Gain During Pregnancy
Weight gain recommendations during pregnancy should be based on pre-pregnancy BMI, with normal-weight women gaining 25-35 pounds total (1.4-2.3 kg in first trimester, then 0.5-0.9 kg/week), underweight women gaining 28-40 pounds, overweight women gaining 15-25 pounds, and obese women gaining 11-20 pounds. 1, 2, 3
Weight Gain Targets by Pre-Pregnancy BMI Category
Underweight Women (BMI <19.8 kg/m²)
- Total pregnancy weight gain: 28-40 pounds (up to 18 kg) 4, 3
- First trimester: 1.4-2.3 kg 4, 2
- Second and third trimesters: 0.5-0.9 kg per week 4, 2
Normal Weight Women (BMI 19.8-26 kg/m²)
- Total pregnancy weight gain: 25-35 pounds 3
- First trimester: 1.4-2.3 kg 2
- Second and third trimesters: 0.5-0.9 kg per week 2
Overweight Women (BMI 26-29 kg/m²)
- Total pregnancy weight gain: 15-25 pounds 3
- Second and third trimesters: gain at less than 50% of the rate for normal-weight women (approximately 0.25-0.45 kg per week) 4, 2
Obese Women (BMI >30 kg/m²)
- Total pregnancy weight gain: 11-20 pounds (5.0-9.1 kg), with some guidelines suggesting 7 kg 4, 2, 3
- Minimal weight gain during second and third trimesters 2
- For severely obese women (BMI 40 kg/m²), emerging evidence suggests weight loss of 6 kg may optimize outcomes, though this contradicts traditional guidelines 5
Trimester-Specific Patterns
First Trimester
- No additional caloric intake needed unless the woman begins pregnancy with depleted body reserves 1, 2
- Weight gain is minimal during this period, with most recommendations targeting 1.4-2.3 kg for underweight and normal-weight women 4, 2
Second and Third Trimesters
- Add 300 kcal/day to baseline energy needs 4, 2
- Protein intake: 0.75 g/kg/day plus an additional 10 g/day 4, 2
- Rate of weight gain increases in a linear manner after 15-20 weeks until term 6
Clinical Risks of Inappropriate Weight Gain
Excessive Weight Gain
- Increases risk of gestational hypertension, pre-eclampsia, gestational diabetes, and large-for-gestational-age babies 1
- Higher rates of cesarean delivery and longer hospital stays 1
- Long-term maternal obesity and childhood obesity in offspring 1
- These risks are independent of pre-pregnancy BMI, meaning even normal-weight women who gain excessively face increased complications 7
Inadequate Weight Gain
- Affects approximately 20% of pregnant women 2
- Increased risk of preterm birth 4
- Difficulties establishing breastfeeding 4
- Higher risk of small-for-gestational-age infants 5
Implementation Strategies
Early Assessment
- Begin weight monitoring at the first antenatal visit to establish baseline measurements 1
- Provide clear information about appropriate weight gain expectations based on pre-pregnancy BMI 1
- Many women report not receiving adequate guidance from providers, with incorrect advice more common among women with high or low pre-pregnancy BMI 8
Nutritional Support
- Iron supplementation: 30 mg/day during second and third trimesters 4, 2
- Folic acid: 400 μg/day for all women of childbearing age 4
- Ensure adequate zinc intake (15 mg/day RDA) 4
- Balanced diet with adequate protein 4
Physical Activity
- Encourage regular physical activity, particularly walking and moderate-to-vigorous activity 1
- Activity should be adapted to the woman's condition 4
Common Pitfalls to Avoid
- Failing to discuss weight gain expectations early in pregnancy, as many women are unaware of guidelines and report receiving no provider advice 1, 8
- Providing incorrect advice based on outdated guidelines or personal bias, particularly for women at BMI extremes 8
- Prescribing hypocaloric diets below 1,200 calories per day, which result in ketonemia and ketonuria 2
- Not addressing psychosocial factors such as negative body image, low self-efficacy, and inaccurate weight perceptions that contribute to excessive gain 1
- Ignoring socioeconomic factors including living in deprived communities, low income, and younger maternal age that increase risk of excessive gain 1
Special Populations
Multiple Gestations
- Women with twins or triplets require higher weight gain targets than singleton pregnancies 1