Obese Mothers At Higher Risk Of Premature Babies
June 12, 2013

Obesity While Pregnant Could Mean Premature Delivery

Brett Smith for redOrbit.com — Your Universe Online

Women who are overweight or obese during pregnancy have an increased risk of preterm delivery, according to a new study in the Journal of the American Medical Association.

"Maternal overweight and obesity has, due to the high prevalence and associated risks, replaced smoking as the most important preventable risk factor for adverse pregnancy outcomes in many countries,” according to the study´s authors. “Preterm birth, defined as a delivery of a (live) infant before 37 gestational weeks, is the leading cause of infant mortality, neonatal morbidity, and long-term disability among non-malformed infants, and these risks increase with decreasing gestational age.”

Despite that dire warning, lead author Dr. Sven Cnattingius, medical professor at Karolinska Institutet in Sweden, suggested that overweight women looking to become pregnant shouldn´t panic over the study´s results.

"For the individual woman who is overweight or obese, the risk of an extremely preterm delivery is still small,” he said. "However, these findings are important from a population perspective. Preterm infants and, above all, extremely preterm infants account for a substantial fraction of infant mortality and morbidity in high income countries."

In the study, researchers looked at data from the Swedish Medical Birth Register on women with live single births from 1992 through 2010. The preterm deliveries were categorized as extremely (22 to 27 weeks), very (28 to 31 weeks), and moderately (32 to 36 weeks). The researchers also looked to see if these preterm deliveries were spontaneous or a medically indicated preterm delivery, meaning a cesarean section before onset of labor or induced labor.

The mothers´ BMI was calculated based on height and weight at the first prenatal visit. The researchers divided the women into six categories: underweight, normal, overweight, obese grade 1, obese grade 2, and obese grade 3.

Of the almost 1.6 million deliveries included in the study, just over 3,000 were extremely preterm, 6,900 were very preterm, and 67,000 were moderately preterm. The researchers determined the risks for extremely, very, and moderately preterm deliveries increased with BMI. Overweight mothers were at the highest risks for extremely preterm delivery.

Medically-induced early births were more frequent at all stages of pregnancy with increasing weight.

"That was, we can see, more or less entirely due to the increased risk of obesity-related maternal complications, " Cnattingius told Reuters Health.

In their conclusion, the researchers said women should take every measure to promote the health of themselves and their unborn child during pregnancy.

"Considering the high morbidity and mortality among extremely preterm infants, even small absolute differences in risks will have consequences for infant health and survival,” they wrote. “Even though the obesity epidemic in the United States appears to have leveled off, there is a sizeable group of women entering pregnancy with very high BMI.”

“Our results need to be confirmed in other populations given their potential public health relevance,” the researchers continued. “Identifying the pathways through which maternal obesity influences offspring health is also needed to provide critical information to specifically target the women at highest risk of preterm delivery.”