Inadequate Pregnancy Weight Increases Infant Death Risk

Researchers in the University of Maryland School of Public Health (College Park, USA) analyzed data collected from 159,244 mothers who gave birth to live, single babies between 2004 and 2008 in order to determine whether there was a link between gestational weight gain (GWG), mothers' body mass index (BMI), and infant mortality. Participants responded to telephone or written questionnaires within nine months after giving birth, with the information recorded in the Pregnancy Risk Assessment Monitoring System (PRAMS).

The results showed that only 34% of women gained the Institute of Medicine (IOM; Washington DC, USA) pregnancy weight gain guidelines for amount of weight during pregnancy. Infant mortality risks were 3.9% among infants of mothers who gained an inadequate amount of weight during pregnancy, 1.2% among infants of mothers who gained an adequate amount of weight, and 0.7% among mothers who gained more than the recommended GWG. The results also showed that the mothers' pre-pregnancy BMI was also a key factor in infant survival.

Mothers who were underweight before pregnancy and gained too little weight during pregnancy had six times the normal rate of infant mortality. Even among overweight women, inadequate weight gain was associated with a two-fold elevation in mortality risk. Only children born to obese women were protected from the effects of inadequate GWG. 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 GWG actually had a 49% reduced likelihood of infant death. The study was published online ahead of print on December 19, 2013, in the American Journal of Public Health.

“Only about a third of women in the US gain weight during pregnancy that is within the recommended range. In order to improve the likelihood of healthy outcomes for mothers and infants, healthcare providers should provide childbearing women with gestational weight gain goals that are specific to their individual BMI,” concluded study coauthor Prof. Sandra Hofferth, MD, and colleagues. “Pregnant women can help ensure the health of their infants by monitoring their weight gain, eating an appropriate amount of healthy foods, and engaging in reasonable physical activity.”

According to IOM guidelines, underweight women should gain between 12–18 kg during pregnancy, while normal weight women are expected to gain 9–15 kg, overweight women 7–12 kg, and obese women 5–9 kg.

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University of Maryland School of Public Health
Institute of Medicine