Antibiotic use in pregnancy linked to childhood asthma risk

Maternal antibiotic use in the second and third trimester of pregnancy was associated with an increased risk for developing childhood asthma, according to research published in Archives of Diseases in Children.

“Antibiotic exposure in mid- to late pregnancy was consistently associated with childhood asthma in vaginally born children and the association appeared to be modified by mode of delivery,” Cecilie Skaarup Uldbjerg, MPH, of the department of public health research unit for epidemiology at Aarhus University, Denmark, and colleagues wrote.

The researchers said that “the findings suggest that the relationship between antibiotics in pregnancy and childhood asthma may be causal, although confounding by indication remains a possibility.”

Uldbjerg and colleagues conducted a cohort study using data from the Danish National Birth Cohort, a longitudinal birth cohort that included approximately 30% of all pregnant women in Denmark during the study period, 1996 through 2002.

Women were enrolled during their first antenatal visit with their general practitioner. They provided information on their characteristics, prenatal exposures and their child’s health through phone interviews conducted at 16 weeks gestation, 30 weeks gestation, 6 months after birth and an online questionnaire when the child was 11 years of age.

A total of 32,651 children with follow-up information available were included in the study.

Among all children, 17% had mothers who used antibiotics during their pregnancy. After adjusting for cofounders such as sex, maternal age, maternal smoking status, maternal BMI, maternal and paternal asthma and sociodemographic characteristics, the researchers determined that these children had higher odds of developing asthma (adjusted OR [aOR] = 1.14; 95% CI, 1.05-1.24) compared with children who did not.

In addition, compared with children who were not exposed to antibiotics during pregnancy, childhood asthma was associated with antibiotic exposure in the second and third trimester (aOR = 1.17; 95% CI, 1.06-1.28), but not exposure during the first trimester.

Uldbjerg and colleagues reported that the association between antibiotic use in pregnancy and childhood asthma was observed among those born vaginally (aOR = 1.17; 95% CI, 1.07-1.28), but not in children born via cesarean section (planned: OR = 0.95; 95% CI, 0.66-1.37; emergency: OR = 0.96; 95% CI, 0.73-1.28).

They found that, compared with children born vaginally who were not exposed to antibiotics in pregnancy, those who were exposed had greater odds of developing childhood asthma that required treatment in the year preceding the 11-year questionnaire (OR = 1.34; 95% CI, 1.21-1.49).

Uldbjerg and colleagues said that changes in the vaginal microbiome may be the root of the association between maternal antibiotic exposure and asthma, but they stressed that more research is needed to assess the underlying mechanisms of the association.

“The profligate use of antibiotics in pregnancy should be balanced against the increasing evidence on adverse long-term health outcomes in the offspring, as well as broader concerns regarding antimicrobial resistance,” they wrote.