Birth outcome of 1886 pregnancies after exposure to phenoxymethylpenicillin in utero.

OBJECTIVE: To examine the risk of congenital abnormalities, preterm birth and low birth weight after exposure to phenoxymethylpenicillin in utero.

METHODS: A population-based follow-up study in the County of North Jutland, Denmark. Birth outcome for 1886 women, who redeemed prescriptions for phenoxymethylpenicillin during pregnancy was compared with the outcome for 9263 women who did not redeem any prescription during pregnancy.

RESULTS: The prevalence of congenital abnormalities in 654 users of phenoxymethylpenicillin with or without other drugs during the first trimester was 4.6% compared with 3.6% in the reference group, giving a prevalence odds ratio of 1.25 (95% CI: 0.84-1.86). The prevalence odds ratio was 1.35 (95% CI: 0.59-3.08) in 131 women who were exposed to phenoxymethylpenicillin only. Nine cardiovascular abnormalities were found, giving an adjusted prevalence odds ratio of 1.74 (95% CI: 0.83-3.65). The prevalence odds ratios of preterm birth and low birth weight were 0.83 (95% CI: 0.66-1.04) and 1.02 (95% CI: 0.71-1.47), respectively.

CONCLUSION: We found no significantly increased risk of congenital abnormalities, including cardiovascular abnormalities, preterm birth, or low birth weight in women who purchased phenoxymethylpenicillin during pregnancy.