Approximately one in every four or five women gains an inadequate amount of weight during pregnancy, according to Dr. Toya Ellis, MD, fellow of the American College of Obstetricians and Gynecologists and OB-GYN at Kaiser Permanente Colorado Region. Some of this is tied to socioeconomic status—women who begin pregnancy without good nutrition, smoke, or lack financial or nutritional resources—but many others are women who purposefully control their weight or just can't gain weight.
"Women in general are certainly spooked about putting on a lot of weight, especially when they hear from media and friends that it completely changes your body or won't come off easily," says Melinda Johnson, a registered dietitian and spokesperson for the American Dietetic Association.
The ABCs of Weight Gain
How much you should gain during pregnancy depends on how much you weighed before conception. The Centers for Disease Control and Prevention (CDC) outline the following formula for calculating your own BMI (use your pre-pregnancy weight):
- Multiply your weight in pounds by 703
- Divide the answer by your height in inches
- Divide this number by your height in inches again. This is your BMI.
Once you know your BMI, the CDC suggests that you use the following parameters to estimate the best target weight gain for your pregnancy:
- Underweight pre-pregnancy: BMI of under 19.8: gain 28 to 40 pounds
- Normal weight pre-pregnancy: BMI of 19.8 to 26: gain 25 to 35 pounds
- Overweight pre-pregnancy: BMI of over 26.1: gain 15 to 25 pounds