Maternal Obesity Increases Infant Mortality

Maternal ObesityObesity during pregnancy increases the risk of health problems such as hypertension, gestational diabetes, premature birth, and Cesarean section, all of which can negatively affect the long-term health of both mother and baby. Now a new study finds that maternal overweight and obesity during pregnancy increases the risk of infant mortality among babies.

As published in the journal BMJ, the study from researchers at the Karolinska University Hospital at the Karolinska Institutet in Stockholm, Sweden and the University of Michigan School of Public Health in Ann Arbor, Michigan sought to investigate associations between maternal overweight and obesity and infant mortality outcomes.

The researchers used a population-based cohort study, analyzing data from 1,857,822 live single births in Sweden between 1992 and 2010 recorded as part of the Swedish Medical Birth Register. Data on maternal weight was collected during the first prenatal checkup along with smoking habits, education, and socioeconomic status.

Maternal body mass index (BMI) was classified using the following scale:

  • Underweight (18.4 or less)
  • Normal weight (18.5-24.9)
  • Overweight (25-29.9)
  • Obesity grade 1 (30-34.9)
  • Obesity grade 2 (35-39.9)
  • Obesity grade 3 (40 or over)

During the study period, 5,428 infant deaths occurred, with two-thirds of the deaths occurring during the first 28 days of life.

Compared with normal weight, overweight and obesity grade 1 modestly increased the risk of infant mortality. Obesity grade 2 and obesity grade 3 more than doubled the risk. Among normal weight mothers, 2.4 infant deaths per 1,000 births occurred. As maternal BMI increased, rates of infant mortality also increased with 5.8 infant deaths per 1,000 births occurring among mothers with obesity grade 3.

In other words, maternal obesity increases the risk of infant mortality.

The researchers additionally found that 11 percent  of infant deaths were associated with maternal overweight and obesity. Congenital anomalies, birth asphyxia, sudden infant death syndrome (SIDS), and infections accounted for 82 percent of the infant deaths in the study. Obesity grade 2 and obesity grade 3 were associated with increased infant mortality as a result of congenital anomalies and SIDS.

The researchers also noted an increase in premature birth among the obese mothers, which may partially explain the increased risk of infant mortality. Prematurity increases the risk of health complications.

Writes Katrine Mari Owe of the Norwegian Institute of Public Health in an accompanying editorial:

“Infants born to overweight or mildly obese women had an increased mortality relative to infants born to normal weight mothers. The increase was modest but statistically significant. Consistent with previous studies,4 5 the greatest risk of infant mortality was observed among the severely obese mothers (grades 2 and 3). In infants born at term, deaths due to birth asphyxia, other morbidities, and congenital anomalies seemed to explain the increased mortality risk. The authors also report an increased risk of preterm birth among overweight and obese women, which further explains the higher infant mortality in these women.”

According to the Centers for Disease Control and Prevention (CDC), more than one-third, or 78.6 million, of adults in the United States are obese.

Concludes Owe:

“Given the high prevalence of overweight and obesity worldwide and the gravity of the risks to the infant, further studies are needed to explore the risks to the infant associated with increased maternal BMI, along with large trials of interventions designed to reduce those risks.”

Another recent study found that exercising during pregnancy reduces excessive weight gain and the possibility of suffering from associated problems.


Adult obesity facts:
Maternal obesity ‘increases risk of infant death’:
Maternal overweight and obesity in early pregnancy and risk of infant mortality: a population based cohort study in Sweden:
Weight in early pregnancy and outcomes in early infancy:

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