But the research doesn't prove cause-and-effect
WEDNESDAY, Feb. 26, 2014 (HealthDay News) -- Babies born by cesarean section seem more likely to be overweight or obese later in life, a new study contends.
The odds of being overweight are 26 percent higher for cesarean babies than those born vaginally, found researchers at Imperial College London, in England.
As the number of cesarean deliveries increases in many countries, pregnant women should be advised about the possible long-term consequences, the researchers said.
"There are good reasons why C-section may be the best option for many mothers and their babies, and C-sections can, on occasion, be lifesaving," senior study author Neena Modi said in a college news release. "However, we need to understand the long-term outcomes in order to provide the best advice to women who are considering cesarean delivery."
Previous studies have suggested that long-term health effects linked to cesarean births include childhood asthma and type 1 diabetes, the news release noted. In examining a possible link between this surgical procedure and obesity, the researchers analyzed information compiled from 15 studies that included more than 38,000 women from 10 different countries.
The new review, published Feb. 26 in PLoS ONE, found that the average body-mass index (BMI) of adults born by cesarean section was about one-half unit greater than the average BMI of babies born vaginally. BMI is a measurement of body fat that takes height and weight into account.
It should be noted that the study found an association between cesarean birth and increased odds of being overweight or obese in adulthood, but it didn't prove cause-and-effect.
The reason for this apparent link remains unclear, the researchers noted, and other factors not considered in their study could play a role.
"This study shows that babies born by C-section are more likely to be overweight or obese later in life," Modi said. "We now need to determine whether this is the result of the C-section, or if other reasons explain the association."
Study co-author Dr. Matthew Hyde suggested possible ways that C-sections might influence later body weight.
"The types of healthy bacteria in the gut differ in babies born by cesarean and vaginal delivery, which can have broad effects on health," Hyde said in the news release. "Also, the compression of the baby during vaginal birth appears to influence which genes are switched on, and this could have a long-term effect on metabolism."
Roughly one in three to four births in England is by cesarean section, the release noted. Meanwhile, 60 percent of pregnant women in China and nearly 50 percent of those in Brazil are having this type of delivery.
The U.S. National Institutes of Health has more about cesarean section (http://www.nlm.nih.gov/medlineplus/cesareansection.html ).
SOURCE: Imperial College London, news release, Feb. 26, 2014