Weight gain during pregnancy ups obesity risk

Gaining too much weight during pregnancy can have consequences that last well after the pregnancy is over.

There's evidence that excess weight gain in pregnancy ups the risk of obesity after delivery, but few studies have looked at the effects of weight gain on obesity risk for more than a couple of years after delivery. To investigate, researchers looked at the body mass index (BMI) of 2,055 Australian women who had delivered babies between 1981 and 1983. BMI is a standard measure of weight in relation to height used to determine if a person is overweight or obese. The researchers used 1990 Institute of Medicine (IOM) recommendations on pregnancy weight gain, which are based on a woman's pre-pregnancy BMI. (The IOM updated these guidelines in 2009.) Women who had gained too much weight during their pregnancy based on the IOM's older guidelines had gained an average of around 20 kilograms (44 pounds) 21 years later, while women who gained a healthy amount of weight put on 14 kilograms (31 pounds); those who gained too little put on about 9 kilograms (20 pounds).

The relationship between pregnancy weight gain and future BMI got stronger once the researchers accounted for a woman's BMI before she got pregnant. It was found that women who gained too much weight during their pregnancy, based on the IOM's guidelines, were twice as likely to be overweight later on, and had a more than four-fold increased risk of being obese. The relationship didn't change even after the researchers accounted for factors such as whether a woman exercised during pregnancy or how long she breastfed her baby.

The researchers concluded that weight gain during pregnancy independently predicts the long-term weight gain and obesity in women.