Febrile seizures affect 2-5% of children between 3 months and 5 years of age. Although genes and environmental factors seem to have a causal role, other causes remain largely unknown. The purpose of the current study was to look at the associations between prenatal exposure to antibiotics and the risk of febrile seizures.
For this population-based cohort study, researchers identified all live singletons born in Denmark between January 1996 and September 2004 (n=551,518), 172,879 of whom had mothers who redeemed a prescription for an antibiotic during their pregnancy (exposed). Information on febrile seizures was taken from the Danish National Hospital Register.
There were slight but statistically significant increased risks of febrile seizures in children born to mothers who took antibiotics during pregnancy, with hazard ratios ranging from 1.06-1.16 for individual subgroups. The only group for which no statistically significant increased risk was found was macrolides, lincosamides and streptogramins. Overall, the use of any systemic antibiotic during pregnancy was associated with a febrile seizure incidence rate of 942 per 100,000 person years, compared to 862 per 100,000 person years in those who were unexposed (difference of 80 events per 100,000 person years).
It is difficult to determine whether the observed results were due to uncontrolled confounding, the prenatal infection, or the treatment (antibiotic). However if a direct effect of the antibiotic was responsible, then more variation between the different groups would have been expected; the authors therefore suggest the risk may be associated with the infection itself (with exposure to antibiotics as a marker). They suggest that the small absolute increase in febrile seizures seen in the exposed group may not be of much importance, unless it indicates that some infections may alter the susceptibility to febrile seizures or infections during the intrauterine time period. They encourage further research on the biomarkers of infection and the specific mechanisms of how maternal infection may affect the developing foetus.