A follow-up study of birth outcome in users of pivampicillin during pregnancy

Background. Pivampicillin is a prodrug which is widely used in Scandinavian countries for oral antibiotic therapy. The pivaloyl moiety has a carnitine depleting effect, which has caused doubts about the safety of administerin g pivampicillin during pregnancy. The aim of the study was to evaluate the risk of congenital malformations in general, preterm delivery and low birth weight in users of pivampicillin. Methods. Seven hundred and ninety-one women who had redeemed a prescription of pivampicillin during their first pregnancy from 1 January 1991 to 31 De cember 1996 were identified in the North Jutland Pharmaco-Epidemiological P rescription Database. By linkage to the Danish Medical Birth Registry and R egional Hospital Discharge Registry we compared their birth outcomes (malfo rmations, preterm delivery and low birth weight) with the outcomes in 7472 reference pregnancies on which the mother had not redeemed any prescription at all during pregnancy. Results. The prevalence of malformations was 5.5% (11 cases) in offspring o f 199 women who had used pivampicillin during the first trimester, and 5.6% (420 cases) in offspring of controls (OR: 0.95, 95% CI: 0.51-1.76). Furthe rmore, we did not find any significant risk of preterm delivery (OR: 0.75, 95% CI: 0.5-1.05) or low birth weight (OR: 0.93, 95% CI: 0.55-1.57). Conclusion. This study showed no increased risk of congenital malformations , preterm delivery or low birth weight in offspring of women who had redeem ed a prescription for pivampicillin during pregnancy.