Obese women less likely to become pregnant and have successful pregnancy, says new findings

Nov 4 2009

Obese women are as much as 28 percent less likely to become pregnant and have a successful pregnancy, according to research that earned a Michigan State University professor a national award.

The findings by Barbara Luke, a researcher in the MSU College of Human Medicine's Department of Obstetrics, Gynecology and Reproductive Biology, focused on data of nearly 50,000 women using assisted reproductive technology.

Luke's findings, which also can be applied to women not using assisted technology, showed women who are simply overweight have a 14 percent less chance of a successful pregnancy.

"The results are not surprising; obesity is a state of inflammation and is not a good environment for conception or fetal development," Luke said. "The key message is to lose weight, prior to conception, and focus on pre-conception health issues.

"Once you become pregnant, the baby is developing in that environment."

Last month Luke was awarded the 2009 Scientific Program Prize Paper for her presentation on maternal obesity research at the 2009 American Society of Reproductive Medicine international meeting in Atlanta. More than 5,000 experts from around the world attended the meeting, which featured nearly 900 abstracts. Only two were selected as program prize papers.

As part of the research, Luke's team looked at the effect increasing body mass index had on a woman's ability to become pregnant using assisted reproductive technology and how obesity affects pregnancy outcomes. They compared outcomes to women with normal body mass index (BMI of 18.5-24.9). Women were classified as overweight (BMI of 25 to 29.9), Class 1 obesity (30-34.9), Class 2 (35-39.9) and Class 3 (40 or greater).

Among the findings:

• Women at Class 3 obesity were 35 percent less likely to become pregnant; Class 2 resulted in a 28 percent less chance; 9 percent for Class 1; and 3 percent for overweight women.
• Of the obese women who were able to become pregnant, the odds of stillbirth were increased more than twofold.
• Among live births, the odds of premature birth significantly paralleled increasing obesity: from 16 percent for overweight women to 34 percent for women at Class 3.

"If you are thinking about starting a family, get into the best physical shape possible." Luke said. "Control the factors you can - such as drinking alcohol and smoking - and remember, body weight is just as important."

Source: Michigan State University