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Antibiotics Used During Pregnancy Linked to Child Obesity

Katlyn Joy |27, November 2014


Researchers from Columbia University have a new study in the International Journal of Obesity connecting the use of antibiotics during pregnancy with later obesity in the child.

A previous study found a link between a mother's antibiotic use during pregnancy and later obesity in the offspring, but this is the first study to specifically look at antibiotic usage during the second and third trimester of pregnancy and later obesity risks.

Women were recruited for the study from the Northern Manhattan Mothers and Children Study from prenatal clinics at Harlem Hospital Center and New York-Presbyterian Hospital. The study covered the years 1998 to 2006, and included 727 mothers of whom 436 were followed along with the child until the child was 7 years of age. Of those 436 mothers and children, 16 percent of the moms took antibiotics during the last two trimesters of pregnancy.

Children whose mothers took antibiotics had an 84 percent higher risk of obesity than those whose mothers did not take the medications. Researchers believe the reason behind the findings is that antibiotic use affects microbes in the mother and in turn reaches the fetus through circulation via the placenta.

Bacterial balances are important in maintaining health and preventing disease, and it's thought overuse of antibiotics can cause imbalances in the bacteria and leads to problems. It seems that interruptions in the flow of proper bacteria from mother to child can give rise to health problems such as obesity.

Noel Mueller, Ph.D. postdoctoral research fellow at Columbia University's Mailman School of Public Health and Institute of Human Nutrition said, "If these findings hold up, they suggest new mechanisms through which childhood growth trajectories are influenced at the earliest stages of development. Our findings should not discourage antibiotic use when they are medically needed, but it is important to recognize that antibiotics are currently overprescribed."

Obesity was determined by BMI, waist circumference and the percentage of body fat in the children, and specifically BMI's above 95th percentile.

In addition to the issue of antibiotic use, researchers also found an increased risk of obesity in the incidences of cesarean section births. After controlling for factors such as ethnicity, birth weight, maternal age, sex, and breastfeeding, researchers found c-sections increased the risk of obesity by 46 percent.

Unlike an earlier study, this research did not find any difference between elective and non-elective Cesareans. "Thus, our findings provide new evidence in support of the hypothesis that Caesarean section independently contributes to the risk of childhood obesity," remarked said Andrew Rundle, Dr.P.H.

The reason why c-sections could contribute to childhood obesity is much the same as the assumed reason for antibiotic use contributing to the problem. As with antibiotics, when a c-section is performed the normal transmission of bacteria and the balance of bacteria between mother and child is disturbed. These disturbances seem to influence the possibility of later obesity.

Said Rundle, "Strategies to reduce medically unnecessary C-sections and to provide the infant with health promoting bacteria after C-section need to be researched. Further research is needed on how mode of delivery, antibiotic use during pregnancy, and other factors influence the establishment of the ecosystem of bacteria that inhabit each of us. This research will help us understand how to create an early platform to support the healthy growth and development of children."

Researchers mentioned that total abandonment of antibiotic use in pregnancy was not the answer, as there are many conditions that require its use for the safety of both mother and child. However, they conclude that more research needs to be done to understand the impact of certain procedures or medications on the bacterial balance and how it affects future weight.

"The current findings in and of themselves shouldn't change clinical practice," Mueller said. "If they hold up in other prospective studies, then they should be part of the equation when considering antibiotic usage. There are many legitimate uses for antibiotics during pregnancy."

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