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The question

Women often blame pregnancy for their having gained weight after becoming mothers. Is there truth to that assertion?

This study

The study involved 28,718 women, most in their mid-20s, who gave birth at least twice in an eight-year period. On average, the women weighed about 153 pounds before their first pregnancy and 168 pounds five years later. Using sociodemographic data to estimate weight increases that would be expected for comparably aged women who did not become pregnant, the researchers determined that those women would weigh 164 pounds at the five-year mark.

Data on women in the study showed that weight gain one to two years after childbirth was in line with expectations for women who had not been pregnant. But from three years after childbirth on, they gained at least a pound a year more than considered normal for age-related weight gain. The researchers wrote that it was unlikely that this gain was attributable to retention of pregnancy weight but rather was the effect of “inconspicuous lifestyle changes of parenthood,” such as finishing the food on a child’s plate, spending time sitting to read or watch a movie with a young child and having less time to exercise and care for themselves.

Who may be affected?

Women who get pregnant and have children. Typically, women gradually gain weight until their mid-60s and then begin to lose, prompted primarily by loss of muscle, which weighs more than fat. However, declines in overall physical activity, especially muscle-building, can contribute to weight gain at any age, as can dietary changes.

Caveats

The study did not include, for comparison, actual women who had not become pregnant, but used mathematical models. The reason for the women’s additional weight gain is a theory only and was not proved by the study.

Find this study

Online in Women’s Health Issues (whijournal.com; search for “maternal weight”).

Learn more about

Information on achieving and maintaining a healthy weight is available at cdc.gov/healthyweight. To learn more about weight gain during pregnancy, go to marchofdimes. org/pregnancy.

The research described in Quick Study comes from credible, peer-reviewed journals.