Excessive weight gain during pregnancy increases obesity risk later

That is the surprising and rather harsh conclusion of a study by researchers from Columbia University's Mailman School of Public Health in New York.

The researchers based their study on data from 302 African-American and Dominican mothers who enrolled in Columbia Center for Children's Environmental Health Mothers and Newborns Study, undertaken in Northern Manhattan and the South Bronx between 1998 and 2013. These women were chosen because they were already at high risk of gaining weight or becoming obese due to an unhealthy diet and unfavorable socio-economic factors.

Pre-pregnancy, 5% of them were underweight, 53% were of normal weight, 20% were overweight and 22% were obese.

Once they become pregnant, 64% of the participants put on more weight than recommended, and 38% were obese seven years later.

The researchers noted that among the women who were not obese pre-pregnancy, those with excessive weight gain during pregnancy had a nearly 400% greater risk of being obese seven years after giving birth.

These effects were even more pronounced among the women who were of normal weight or underweight pre-pregnancy. The team showed, for example, that excessive weight gain in women of normal body weight (a body mass index of 22) was associated with a 3% increase in body fat and 12 pounds greater weight seven years later.

In contrast, the researchers noted that in the case of the women who were already overweight, the weight added during pregnancy was not associated with a significant increase in weight or body fat.

"Gestational weight gain greater than the IOM (Institute Of Medicine) recommendations has long-term implications for weight-related health" explained Elizabeth Widen, a co-author of this study. "These findings also suggest that normal and modestly overweight women may be more physiologically sensitive to effects of high gestational weight gain and, therefore, need to be further supported to gain weight appropriately during pregnancy".

The recommendations from the IOM in the US are for an ideal weight gain of 25-26 lbs for a woman of normal weight and 15-25 lbs for an overweight woman. In the US, 47% of women exceed these guidelines.