The recommended weight gain for pregnancy depends on a woman’s pre-pregnancy weight, the number of babies she is carrying, and on her own nutrient needs if she is still a teen. Based on BMI, for one baby, an adult woman needs to gain:

• Underweight (BMI less than 20): 28 – 40 pounds
• Normal weight (BMI 20 – 25): 25 – 35 pounds
• Overweight (BMI 26 – 29): 15 – 25 pounds
• Obese (BMI greater than 29): 11 - 20 pounds

Dieting during pregnancy is not recommended, but the weight gain recommendations for obese women are being tested. The Healthy Moms Study, an ongoing four-year trial, is aiming for zero weight gain or at least no more than 3 percent of their baseline weight.  Read about the Healthy Moms Study in the New York Times.