In the News: Antibiotic Exposure and Obesity Risk

Over the last few days, you may have seen or heard headlines like Could Antibiotics Be A Factor In Childhood Obesity?  and Antibiotics Too Soon May Set Babies Up for Obesity. These headlines are referring to research findings published this week in the International Journal of Obesity. (Trasande 2012) In today’s post, we’ll breakdown the study results and explain what it means for you and your baby.

Study Details

The data in this report were part of the ALSPAC study, a large, long-term health study in the United Kingdom. In the early 1990’s, more than 14,000 pregnant women were recruited and since then, the researchers have been monitoring their children’s health and development. For this report on the relationship between antibiotic use and weight status, the researchers used data from 11,532 children, excluding children who were under 5.5lbs at birth and those without antibiotic exposure data.

The researchers were interested at examining how exposure to antibiotics during 3 different age ranges (0-6 months, 6-14 months, and 15-23 months) was related to body mass over the first 7 years of life. They asked the parents of the children about antibiotic exposure in surveys that were mailed to their homes. To determine the children’s weights, the researchers used weight-for-length measurements at at approximately 2, 10, and 20 months of age and Body Mass Index (BMI) at 38 months and 7 years of age. They also considered other factors that could influence weight status and factored those into their analysis to help highlight the relationship between the antibiotic exposure and weight status.

Study Results

Here is a list of the major study findings:

• About 32% of the children received antibiotics before 6 months of age, increasing to almost 75% by 23 months of age.
• Children who were never breastfed or had mothers who smoked during the first trimester of pregnancy were more likely to be exposed to antibiotics before 2 years of age.
• After accounting for other risk factors, children exposed to antibiotics before 6 months of age were 22% more likely to be overweight at 38 months.
• No consistent association was shown between overweight and antibiotic exposure from 6-14 or 15-23 months.

How does exposure increase risk of obesity?

Although this study was able to show a relationship between early antibiotic exposure and risk of obesity in a very large group of children, this is one of the first studies to look at this relationship, so more studies are needed to confirm the findings. Furthermore, the study was not set-up to determine why the association exists, so it is not possible to explain how exposure to antibiotics increases obesity risk. Using what is known about how the digestive tract develops and data from studies of antibiotic exposure in farm animals, the authors suggest that it is possible that the antibiotics change how the young infants’ intestines develop, but more research is needed to determine how and why this relationship occurs.

What does this mean for you and your baby?

While the study findings suggest that babies who are given antibiotics before 6 months have higher risk for overweight, the increased risk is relatively small and the connection between antibiotic exposure and overweight is inconsistent. If other studies confirm this finding, this would mean that early exposure to antibiotics might be a factor (among other factors) contributing to the increases in childhood obesity over the last decade. Since the researchers could not identify why antibiotic use was related to childhood obesity, they don't know if other important things (like why or how long the antibiotics were given) might make a difference. Antibiotics used to be given to babies more often than they are today and your doctor may not think your baby needs them for common illnesses. If your doctor does recommend antibiotics for your baby, take time to discuss your concerns so you can make a decision together that you feel comfortable with.

Reference: 
Trasande L. et al. Infant Antibiotic Exposure and Early-Life Body Mass. Int J Obes (Lond). 2012 Aug 21.  [Epub ahead of print]