Antibiotics for Baby May Make for Husky Tot
By Nancy Walsh, Staff Writer, MedPage Today, Published: August 23, 2012,
Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston and Dorothy Caputo, MA, BSN, RN, Nurse Planner
- A longitudinal study of children in the U.K. found that exposure to antibiotics in the first 6 months of life was associated with increased body mass out to 38 months.
- Note that other early medication exposure, such as eye drops, did not appear to correlate with increased body mass.
Children given antibiotics in the first 6 months of life have increased body mass through toddlerhood, which may have implications for their later health, a large study suggested.
After adjustment for multiple potential confounders including parental weight, breastfeeding, and childhood sedentary behavior, antibiotic use during the first 6 months of life was associated with a 22% increased likelihood that the child would be overweight at 38 months of age (OR 1.22,P=0.029), according to Leonardo Trasande, MD, and colleagues from New York University in New York City.
By 38 months the risk for obesity also was elevated with exposure to antibiotics during the first 6 months, although not to a statistically significant degree (OR 1.23,P=0.097), the researchers reported online in the International Journal of Obesity.
Exposure beyond 6 months, in contrast, appeared to have no effect on body mass, suggesting that the first 6 months is "a window of special vulnerability to exposure," they noted.
In recent years, interest has stirred in the "human microbiome," which consists of the thousands of microbial residents in the human gut that are crucial to various metabolic processes, proper immune function, and development and differentiation of cellular activity.
It also has become increasingly clear that neonatal colonization of the microbiome is crucial, raising questions about the effects of interference through a lack of breastfeeding or the use of antimicrobial agents during the first months of life.
"While the composition of the microbiota of adults appears relatively stable, the microbiota of children may be considerably more variable and more vulnerable to antibiotic perturbation," Trasande's group wrote.
Furthermore, farmers have long known that adding antibiotics to animal feed early in life causes rapid weight gain in livestock.
To examine the effects of exposure in young children, the researchers analyzed data from a longitudinal study of children in Avon, England. They identified 11,532 children born in 1991 and 1992 weighing at least 2,500 g (6 lbs.).
More than 90% of the children were white, 26% were breastfed for at least 6 months, and rates of parental obesity were lower than in the general U.K. population.
Parents were asked about children's antibiotic use during three time periods: before 6 months of age, between 6 and 14 months, and between 15 and 23 months.
The use of antibiotics was not associated with obesity-related factors such as maternal weight and socioeconomic status, but was linked with maternal smoking and a lack of breastfeeding.
By 6 months, 31.9% of children had been treated with an antibiotic, and by 23 months 74.3% had been exposed.
Birth weights and birth weight-for-length Z-scores were similar among exposed and unexposed neonates.
At 10 months, children with early-life exposure to antibiotics had an increase in weight-for-lengthZ-scores of 0.106 standard deviations (SD), while at 20 months the increase was 0.083 SD (P<0.001 for both).
By 38 months, body mass index Z-scores in the exposed infants showed an elevation of 0.067 SD (P=0.009).
This represented only a modest increase in weight of approximately 90 g, or about 0.2 lbs., and while that may be a small difference for the individual, the population effect could be estimated at an increase of 1.62% in rates of overweight and of 0.72% for obesity, the researchers explained.
However, unlike in a previous study, the increased body mass no longer was seen when the children reached 7 years of age.
This may have resulted from differences in antibiotics used or method of administration, according to the researchers, who noted an association between obesity in adults and intravenous vancomycin, though not amoxicillin.
The researchers also examined the possibility that parental willingness to give medications to their children might have influenced their results. To do so, they looked at whether the use of antipyretics or eye ointments was associated with increases in body mass, and found no relationship.
Limitations of this analysis included the possibility of unidentified confounders and the inclusion only of children weighing at least 2,500 g (6 lbs.) at birth.
Moreover, the influence of antibiotics may have been underestimated, because the use of these drugs has been rising in the U.K. by more than 4% annually since 2000, according to the researchers.
"The effects of today's more frequent antibiotic exposure in early life may therefore be greater, and transgenerational impacts of continued antibiotic use could compound effects," they observed.
They called for further study to clarify the effects of early and later exposures, "and to quantify the life-course implications for body mass and cardiovascular risks at the population level."
The authors declared that they had no competing financial interests or relationships.
Primary source: International Journal of Obesity
Trasande L, et al "Infant antibiotic exposures and early life body mass" Int J Obesity 2012; DOI: 10.1038/ijo.2012.132.