Pregnancy Weight Linked to Heavy Kids

April 2, 2007 -- Mothers-to-be who follow widely accepted recommendations for weight gain during pregnancy may still be putting their babies at risk for becoming overweight early in life, Harvard Medical School researchers report.

Babies in the Harvard study born to women who gained too much weight, or even appropriate amounts of weight under current guidelines, were four times as likely to become overweight early in childhood as babies born to women who gained less weight than the guidelines recommend.

Though the findings must be confirmed, one of the study’s researchers tells WebMD that policymakers should consider revising the current weight-gain guidelines.

“To individual moms I would say definitely don’t over-gain during pregnancy,” says Emily Oken, MD, MPH. “In our [study] population, more than half of the women gained more than what was recommended, which we think may already be too generous.”

Low-Birth-Weight Concerns

The current federal guidelines, published in 1990, call for more weight gain during pregnancy than had been recommended in the past. The revision was motivated by concerns that low weight gain led to babies of low birth weight.

Using standard body mass index (BMI) measures of body weight, the guidelines recommend the following pregnancy weight gains:

• 28 to 40 pounds for underweight women
• 25 to 35 pounds for women of normal weight
• 15 to 25 pounds for overweight women
• At least 13 pounds for obese women

Pregnancy weights have been increasing over the last two decades, and the rate of obesity among young children has reached epidemic levels.

“We have seen an increasing trend towards obesity even in infants, suggesting that the pressures encouraging weight gain in children aren’t confined to fast food, too much TV, and too little exercise,” Oken says.

Oken and colleagues examined pregnancy weight and child outcomes in 1,044 mother-child pairs followed through pregnancy until the children reached age 3.

Just more than half of the women (51%) gained more weight during pregnancy than the guidelines called for, while 35% gained within the guidelines and 14% gained less weight than recommended.

Even after adjusting for childhood obesity risk factors like high birth weight, children born to women who gained the recommended amount of weight or more were at increased risk for being overweight by age 3.

“We know babies born to women who gain a lot of weight during pregnancy tend to have higher birth weights, but that didn’t explain the increases we saw,” Oken says.

Pre-Birth Programming

Boston obstetrician Laura E. Riley, MD, tells WebMD that the researchers make a good case for a link between a mother’s pregnancy weight gain and her child’s risk for becoming overweight.

She points out that recent birth statistics suggest that the average birth weight of babies in this country has remained steady, while infants are getting fatter.

Riley is the medical director of labor and delivery at Massachusetts General Hospital.

“If the average birth weight is still 7 to 8 pounds, and these babies are fat at 2 months, this suggests to me that there is some kind of in utero programming going on,” she says. “I want to see more research on this, but I am pretty convinced and incredibly concerned.”

Riley agrees that it may be time to revisit the guidelines on pregnancy weight gain, but she is not convinced this will have much of an impact.

She says most pregnant women probably aren’t getting an accurate picture of how much weight they should gain based on their weight.

“I think the general message that everyone is getting is that they should gain 25 to 35 pounds,” she says. “That may be good advice for some women but not for everyone.”