Weight a Factor in Reducing Infant Death

Issue Date: 
December 7, 2015

Every year, approximately 24,000 infants die in their first year of life in the United States. The U.S. rate of 6.1 deaths per 1,000 live births ranks 26th in the world, despite a 20 percent decline in the U.S. infant mortality rate from 1990 to 2010. 

Now, findings from the University of Pittsburgh Graduate School of Public Health suggest that achieving a healthy weight before becoming pregnant and gaining an appropriate amount of weight during pregnancy significantly reduce the risk of the baby dying in his or her first year of life.

The research results, published online in November and slated to appear in the February 2016 issue of the journal Obesity, highlight the need for a comprehensive approach to obesity reduction among women of reproductive age that includes weight counseling before conception and during pregnancy. The research was funded by the National Institutes of Health.

Lisa Bodnar“One in three women start pregnancy at an unhealthy weight, and more than half of women gain either too much or too little weight during pregnancy,” said Lisa Bodnar, associate professor in Pitt Public Health’s Department of Epidemiology. “While more research needs to be conducted, we are hopeful that this study can be used to start a dialogue between physicians and women on the importance of not only gaining a healthy amount of weight while pregnant, but also reducing excess weight before they become pregnant as a potential way to improve infant survival.”

Bodnar was lead author of the report on the research, which was completed in partnership with researchers from University of British Columbia, University of California at Berkeley, and Emory University.

Bodnar and her colleagues examined records from more than 1.2 million births that occurred from 2003 to 2011 in Pennsylvania, including 5,530 infant deaths. Infant deaths were defined as the death of a child before his or her first birthday. 

The mothers were classified as underweight, normal weight, overweight, or obese, which was divided into three grades, based on their pre-pregnancy body mass index—a measure of body fat based on weight and height. In each weight group, the researchers also examined the impact on infant mortality when women gained significantly more or less weight during pregnancy than Institute of Medicine guidelines, which, for example, recommend a weight gain of 25 to 35 pounds for normal-weight women and 11 to 20 pounds for obese women.

In all the weight classes except the most obese, gaining less than or much more than recommended increased the risk of infant death. However, even when obese women gained the optimal weight during pregnancy, their risk of infant death was still about twice as great as that of women who began pregnancy at a normal weight.

“Obesity and infant mortality are among the most critical public health issues today,” said co-author Katherine Himes, assistant professor in Pitt’s Department of Obstetrics and Gynecology in the School of Medicine. “Our study highlights the importance of discussing weight loss with obese women prior to pregnancy because losing weight during pregnancy may increase the risk of a baby dying. We hope this information empowers providers, including obstetricians, family doctors, and primary care physicians, to discuss the benefits of preconception weight loss with all obese, reproductive-age women.’’