Oral antibiotic prescribing during pregnancy in primary care: UK population-based study

To examine patterns of prescribing of oral antibiotics during pregnancy and to determine whether women were more or less likely to receive specific types of antibiotics in pregnancy than in the years before and after pregnancy. Finally, to identify socio-demographic factors associated with antibiotic prescribing in pregnancy.

We identified 114 999 women who gave live birth between 1992 and 2007 in The Health Improvement Network (THIN) UK primary care database. Antibiotic prescribing during pregnancy was estimated for each calendar year between 1992 and 2007. Self-controlled case series (SCCS) methodology was used to compare antibiotic prescribing during pregnancy with the years before and after pregnancy, and Poisson regression to examine association between demographic factors and antibiotic prescribing.

A third of pregnant women received at least one antibiotic prescription during pregnancy. In each trimester, 14% of women received at least one antibiotic. Prescribing of antibiotics was lower in pregnancy than during a comparable period 1 year earlier [incidence rate ratio (IRR) 0.91 (95% CI 0.90-0.93)], but some antibiotics were prescribed more frequently in pregnancy: broad-spectrum penicillins [IRR 1.46 (1.42-1.49)]; cephalosporins [IRR 2.22 (2.13-2.31)]; and antibiotics for urinary tract infections [IRR 2.29 (2.01-2.61)]. Respiratory, urinary, skin and ear infections were the commonest indications. Urinary indications increased and respiratory, skin and ear infection indications declined during pregnancy, although a large proportion were prescribed without indication. Young age and social deprivation were associated with increased antibiotic prescribing during pregnancy.

Antibiotic prescribing is widespread in pregnancy although marginally reduced compared with the year before pregnancy. There were substantial changes in types of antibiotics as well as in their indications during pregnancy. This may be explained by changes in threshold for treatment, diseases, detection and recording. Younger women and women from deprived areas were most likely to receive antibiotics in pregnancy.