Babies born to women who do not gain enough weight during pregnancy are at a greater risk for dying before their first birthday, according to a new study. The study examined the relationship between how much weight a woman gains during pregnancy, her body mass index before and during pregnancy, and the rate of infant mortality.

Scientists at the University of Maryland School of Public Health looked at the health records of more than 159,000 women who gave birth to live single babies between the years of 2004 and 2008. Study participants answered written or telephone survey questions within nine months of delivering their babies. The researchers stored the data they collected in the Pregnancy Risk Assessment Monitoring System for later use.

About one-fourth of the study participants had not gained enough weight during pregnancy. The researchers discovered these women were at higher risk for having a baby that died in infancy – 3.9 percent – than were women who gained the appropriate amount of weight, who saw infant mortality rates of 1.2 percent. Women that gained too little weight during pregnancy had a higher risk for infant mortality than even those women that gained too much, who reported infant mortality rates of 0.7 percent..

Published in the American Journal of Public Health, the study demonstrates that some weight gain is appropriate during pregnancy for all but the most obese women. Authors say the study underscores the importance of establishing and meeting weight gain goals specific to a woman’s body mass index (BMI), during pregnancy.

The guidelines published by the Institute of Medicine suggest underweight women gain 28 to 40 pounds during pregnancy. Women who are normal weight should gain somewhere between 25 and 35 pounds. Overweight and obese women should still gain a little weight during pregnancy – 15 to 25 pounds for overweight women and 11 to 20 for obese individuals.

Researchers noted only about a third of study participants gained the recommended amount of weight during pregnancy. Nearly one-fourth of the women gained too little while another 41 percent put on too much weight.

Source: University of Maryland. "Inadequate pregnancy weight gain a risk factor for infant mortality." Medical News Today. MediLexicon, Intl., 31 Dec. 2013. Web. 9 Jan. 2014.