A Bigger Mama Means a Bigger Baby

Overweight pregnant women are more likely to give birth to larger babies

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Worried about having to push an exceptionally large baby come delivery day? One thing you can do to make this less likely is to be a normal weight before you're pregnant.

A recent study has confirmed what several other studies have found lately: that being overweight before and during pregnancy makes it more likely that you'll have a bigger baby, which comes with its own possible complications.

"Get to a healthy weight before you getting pregnant."

Ravi Retnakaran, MD, a researcher at Mount Sinai Hospital in New York City, and colleagues, wanted to find out the risk factors of having a large baby among women with gestational or regular diabetes during their pregnancy since past research shows these women are more likely to have larger babies.

They defined above average weight as a baby that's over 4 kg, or 8.8 pounds at birth. Having a larger baby increases the risk of having to deliver by cesarean section or having other complications or issues, such as a larger tear during birthing.

For the study, the researchers looked at 472 women, including 368 with normal glucose levels and 104 who had some level of glucose intolerance, indicating gestational diabetes.

The factors most strongly correlated a larger baby among women without gestational diabetes with the extra weight a mother carries before she became pregnant and the amount of weight mothers gain during their pregnancy.

Women were 1.16 times more likely to have a larger baby for every one point increase of their BMI (measured in kg/meters) before pregnancy. Each 1 kg (2.2 pounds) a woman gained during pregnancy made her 1.12 times more likely to give birth to a larger baby.

While higher glucose levels and lipid levels did have a small effect on whether a woman had a large baby, this connection was not very strong and was overshadowed by the impact of a mother's pre-pregnancy weight and weight gain.

"These data suggest that maternal weight and its associated circulating factors have a greater impact on infant birth weight than do mild glucose intolerance and lipid levels in women without gestational diabetes," Dr. Retnakaran wrote.

"In the context of the current obesity epidemic, these data support the importance of targeting healthy body weight in young women as a strategy for reducing the risk of excessive fetal growth and [overweight babies]," the authors wrote. "Furthermore, these findings suggest that, in the care of overweight or obese women in pregnancy, closer monitoring of weight gain during pregnancy may be warranted."

The study appeared online May 22 in the Canadian Medical Association Journal (CMAJ). The research was funded by grants from the Canadian Institutes of Health Research. The authors declared no competing interests.

Reviewed by: 
Review Date: 
May 22, 2012
Last Updated:
July 31, 2012