Antibiotic exposure in third trimester linked to asthma in offspring: BMJ
Denmark: In utero exposure to antibiotics in mid-to-late pregnancy increases asthma risk in vaginally born children, finds a recent study in the BMJ journal Archives of Disease in Childhood. According to the study, delivery mode may modify this association. No association was found for antibiotic exposure in the first trimester of pregnancy.
The use of antibiotics during pregnancy is suggested to increase asthma risk in offspring but findings are not consistent. Previous studies differed significantly in sample size, research design, diagnostic methods, follow-up period, and timing of exposure in pregnancy.
Cecilie Skaarup Uldbjerg, Aarhus University, Aarhus, Denmark, and colleagues aimed to investigate if antibiotic exposure during pregnancy is associated with childhood asthma and if this relationship was conditional on mode of delivery and timing of exposure.
The researchers recruited participants from the Danish National Birth Cohort (DNBC), conducted in 1996 to explore the impact on health of prenatal and early life exposures. The mums-to-be were referred to the DNBC by their family doctor at their first antenatal visit at 6-10 weeks of pregnancy between 1996 and 2002. Of the 96,832 children born to these women, 32,651 were included in this study.
Relevant health and lifestyle information about the mothers, prenatal exposures, and child health was obtained by telephone and online questionnaires.
Phone interviews were carried out at 16 and 30 weeks of pregnancy and once after the birth. The mums then filled in online questionnaires about their children's health when they were 11 years old.
Key findings of the study include:
- A total of 5522 (17%) children were born to mothers exposed to antibiotics during pregnancy.
- In adjusted analyses, children born to exposed mothers had higher odds of asthma (OR 1.14).
- There was no association with antibiotic exposure in the first trimester (OR 1.02), but higher odds were observed for antibiotic exposure in the second to third trimester (OR 1.17), compared with unexposed children.
- The overall association between antibiotics during pregnancy and childhood asthma was only observed in vaginally born children (OR 1.17) but not in caesarean section born children (planned caesarean section: OR 0.95; caesarean emergency: OR 0.96).
- In exposed vaginally born children, the odds for childhood asthma requiring treatment during the preceding year were 34% higher (OR 1.34), compared with unexposed vaginally born children.
"Antibiotic exposure in mid-to-late pregnancy is associated with higher odds of childhood asthma in vaginally born children. Mode of delivery may modify the association," concluded the authors.
The study titled, "Antibiotic exposure during pregnancy and childhood asthma: a national birth cohort study investigating timing of exposure and mode of delivery," is published in the journal Archives of Disease in Childhood.