Infant Mortality Affected by Mother's Inadequate Weight Gain During Pregnancy

A new study suggests that women who do not gain enough weight during pregnancy are at risk of losing their baby within the first year of life.

Nearly 160,000 mothers were included in the study, which is published in the American Journal of Public Health. Nearly one-quarter of the mothers surveyed gained too little weight during pregnancy and were found more likely to have a baby that died in infancy than women who gained a normal or even excessive amount of weight during pregnancy.

"Our study showed that gaining too little weight during pregnancy is a risk factor for infant mortality for all but the heaviest women," said Regina Davis, associate executive director of the American Public Health Association. Davis and three of her colleagues involved in the research are affiliated with the University of Maryland's Maternal and Child Health Program.

The study's senior author, Sandra Hofferth, said that the study results emphasized that pregnant women have weight gain goals that are specific to their personal body mass index (BMI). The study examined the relationship between gestational weight gain, mothers' BMI before and during pregnancy, and infant mortality rates.

According to the Institute of Medicine (IOM), an underweight woman should plan to gain between 28 and 40 pounds during pregnancy. Normal weight women should plan to gain between 25-35 pounds. Overweight women should plan to gain between 15-25 pounds, while obese women should plan on only gaining between 11-20 pounds, according to the IOM.

The University of Maryland study revealed that only one third of women gained an amount of body weight that was within the recommended weight gain guidelines for their body size. Most women - 41 percent - gained too much weight, while 25 percent did not gain enough weight, the researchers found.

Knowing this, the researchers sought to determine if there were links between a woman's gestational weight gain, her BMI and infant mortality.

The researchers found that in the study sample of 159,244 mothers who gave birth to live, single babies between 2004 and 2008, infant mortality risk was 3.9 percent for babies born to women who were considered to gain an inadequate amount of weight.

From there, the infant mortality risk lowered to 1.2 percent among mothers who gained adequate weight and 0.7 percent among mothers who gained more than the recommended amount of weight.

BMI also played a role in infant mortality risk, the researchers learned. Mothers who were underweight before pregnancy and gained too little weight during pregnancy had six times the normal risk of infant mortality.

"Even among overweight women, inadequate weight gain was associated with a two-fold elevation in the risk of mortality. Only children born to obese women were protected from the effects of inadequate weight gain," the researchers said in a statement. "In contrast, gaining more than the recommended amount of weight was not associated with risk to the infant among mothers in any weight category. Obese mothers who gained an excessive amount of weight actually had a 49 percent reduced likelihood of infant death."

The research team stressed that pregnant women can help ensure their infant's health having a weight gain plan, eating healthy foods, and getting a reasonable amount of exercise.