Inadequate Weight Gain in Pregnancy Increases Infant Mortality

Babies whose mothers do not gain enough weight during pregnancy are at an increased risk of death within their first year of life, a recent study found.¹

Among women who gained an inadequate amount of weight, the risk of infant mortality was 3.9%, according to the findings. Infant mortality risks were 1.2% for babies born to mothers who gained the proper amount of weight and 0.7% for mothers whose weight gain exceeded the recommended guidelines, the study reported. Obese mothers who gained too much weight reduced the likelihood of infant death by 49%.

While gaining more weight than recommended was not a risk factor for infant mortality, the authors noted that excess weight gain may be related to subsequent maternal health problems and should be avoided.

"It is important that childbearing women have pregnancy weight gain goals that are specific to their individual BMI," said Dr. Sandra Hofferth, the study's senior author, in a press release.

The researchers, who analyzed data collected from 159,244 mothers who gave birth to live, single babies between 2004 and 2008, also found that pre-pregnancy BMI was a factor in infant survival.

Specifically, women who were underweight before becoming pregnant and who gained too little weight during pregnancy had an infant mortality rate that was 6 times the normal rate. Likewise, there was a 2-fold increase in the risk of infant mortality among babies born to overweight women who had an inadequate weight gain.

Only children born to obese women were protected from the effects of inadequate weight gain, the researchers found.

The researchers used the Institute of Medicine guidelines for pregnancy weight gain, which indicate the following²:
- Underweight women should gain 28 to 40 pounds.
- Normal weight women should gain 25 to 35 pounds.
- Overweight women should gain 15 to 25 pounds.
- Obese women should gain 11 to 20 pounds.

Just 34% of the women in this study gained the recommended amount of weight during pregnancy, reported the study authors.

Pertinent Points:
- Gaining too little weight during pregnancy increases the risk of infant death.
- Researchers analyzed data collected from 159,244 mothers and found the risk of infant death was 3.9% among babies born to mothers who gained too little compared with a risk of 1.2% for babies born to mothers who gained within the Institute of Medicine’s specified range.
- Infants born to underweight, normal-weight, and overweight women with inadequate gestational weight gain were more likely to die during infancy than infants born to women with adequate weight gain.

References:

References
1. Davis RR, Hofferth SL, Shenassa ED. Gestational weight gain and risk of infant death in the United States. Am J Public Health. 2013;doi:10.2105/AJPH.2013.301425.

2. Institute of Medicine. Weight gain during pregnancy: reexamining the guidelines. May 2009. Available here.