The amount of weight to gain during pregnancy depends on pre-pregnancy body mass index (BMI):
- Underweight (BMI < 18.5): Gain 28 to 40 pounds (13 to 18 kg)
- Normal weight (BMI 18.5-24.9): Gain 25 to 35 pounds (11 to 16 kg)
- Overweight (BMI 25-29.9): Gain 15 to 25 pounds (7 to 11 kg)
- Obese (BMI 30 or more): Gain 11 to 20 pounds (5 to 9 kg)
For twin pregnancies, higher weight gain is recommended. Most women gain 2 to 4 pounds in the first trimester, then about 1 pound per week thereafter. The gained weight includes the baby, placenta, amniotic fluid, breast tissue, increased blood volume, fat stores, and uterus growth. Caloric needs also increase with pregnancy stages, generally 1800 calories/day in the first trimester, 2200 in the second, and 2400 in the third trimester. It is advisable to consult with a healthcare provider to personalize these recommendations based on individual health and pregnancy circumstances.
