The amount of weight you should gain during pregnancy depends on your weight before you got pregnant. Your health care provider will advise you on a healthy weight gain based on your current weight, diet, and activity level. Typically, weight gain should be gradual throughout pregnancy, with a total of about 0.5 to 2 kilograms in the first trimester and 1 to 2 kilograms each month in the second and third trimesters.
In 2009, the Institute of Medicine released new recommendations for total weight gain during pregnancy, based on pre-pregnancy body mass index (BMI), a measure that combines height and weight. According to these recommendations:
• Women in a healthy weight range before getting pregnant should gain between 11 and 16 kilograms.
• Women who are underweight or overweight before becoming pregnant may need to gain more.
• For underweight women with a BMI of less than 18.5, total weight gain should be between 13 and 18 kilograms.
• Overweight women (BMI between 25 and 29.9) should gain between 7 and 11 kilograms.
• Women with a BMI greater than 30 should gain between 5 and 9 kilograms.
New recommendations issued by the American Congress of Obstetricians and Gynecologists suggest that overweight and obese women may be able to gain even less than what is recommended and still have a healthy infant. It's important for women to discuss with their health care provider how to maintain a healthy weight during pregnancy, as being overweight or obese can affect pregnancy outcomes and the long-term health of the mother and infant. An NICHD study found that women who were obese before pregnancy were more likely to have infants born with congenital malformations such as heart problems and neural tube defects.