Children born to women who took antibiotics in mid or late pregnancy may have a raised risk of asthma, researchers report today.
Ms Cecilie Skaarup Uldbjerg of Aarhus University, Denmark, and her team explain in Archives of Disease in Childhood today (10 February) that in Denmark, as elsewhere, antibiotic use in pregnancy is increasing.
Currently the rate in Denmark is 37% of pregnancies. Often these prescriptions are necessary, but health care providers are urged to cut down on unnecessary antibiotic use.
The researchers looked at the possible link with childhood asthma using information on 32,651 children born from 1996 to 2002.
In total, 17% of the mothers took antibiotics. This group of children had a 14% higher risk of asthma. When examined more closely, antibiotics in the first trimester did not raise the risk. In addition, the link was not seen in children born by Caesarean.
For vaginally born children whose mothers took antibiotics in the middle or last trimester, the chance of needing treatment for asthmas in the preceding year was 34% higher than for other children.
The authors write: "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."
They believe that the increased risk may be due to the effects of antibiotics on the maternal microbiome, passed to the infant during vaginal birth. But they add, "the specific mechanisms underlying prenatal antibiotics and long-term effects on immune-related child health outcomes remains uncertain".
Uldbjerg, C. S. et al. Antibiotic exposure during pregnancy and childhood asthma: a national birth cohort study investigating timing of exposure and mode of delivery. Archives of Disease in Childhood 10 February 2021; doi: 10.1136/archdischild-2020-319659
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