BACKGROUND: Antibiotic use has been associated with adverse reproductive effects in animals; however, there are few studies in humans.
OBJECTIVES: To examine the effect of preconception intake of antibiotics on female fecundability.
METHODS: We examined this relation in a prospective cohort study of 5,279 Danish pregnancy planners who had been trying to conceive for ≤6 cycles at study entry. Participants completed a baseline questionnaire and bi-monthly follow-up questionnaires for up to 12 months or until reported pregnancy. From the Danish National Prescription Registry, we retrieved data on prescribed antibiotics using Anatomical Therapeutic Chemical Classification System codes. Exposure was defined as redemption of ≥1 prescription for antibiotics (J01), penicillins (J01C), macrolides (J01F), and sulphonamides (J01E) within 30 and 90 days before study entry. We used proportional probabilities models to compute adjusted fecundability ratios (FRs) and 95% confidence intervals (CI). We adjusted for demographics, lifestyle factors, parity and intercourse frequency.
RESULTS: Within 30 and 90 days before study entry, 252 (4.8%) and 675 (12.8%) participants redeemed a prescription for antibiotics, respectively. Compared with women not prescribed antibiotics, the adjusted FR (95% CI) for women redeeming ≥1 prescription for antibiotics within 30 days was 0.90 (0.78-1.04), and the adjusted FRs (95% CI) for 1 and ≥2 prescriptions redeemed within 90 days were 0.99 (0.90-1.09) and 0.90 (0.74-1.09), respectively. For use of penicillins, macrolides, and sulphonamides within 30 days, the FRs were 0.84 (0.70-1.01), 1.27 (0.88-1.83) and 1.02 (0.72-1.45), respectively. Based on the 90-day window the FR (95% CI) for penicillin was 1.00 (0.90-1.11).
CONCLUSIONS: Preconception penicillin use within 30 days was associated with reduced fecundability. The extent to which this finding reflects the effect of penicillin itself or factors related to penicillin use warrants further research.
