Utilisation of teratogenic medicines before and during pregnancy in Australian women.

The study included 191 588 pregnancies (145 419 women). Prevalence of exposure to D/X medicines anytime during pregnancy was 2.0% (<20 pregnancies category X), decreasing from pre-pregnancy (3.8-6.0%) to first trimester (1.5%), further decreasing in second and third trimesters (0.8% and 0.6% respectively). We observed large reductions in antibiotic prevalence but only modest reductions for psychotropics and antilipidemic agents (all category D). Our results suggest higher use of potentially teratogenic medicines (category D) than those strictly contraindicated for use (category X), during pregnancy. Overall, use was higher in the first trimester than the rest of pregnancy. The high prevalence of potentially contraindicated psychotropics in all three trimesters may suggest a higher benefit-to-risk ratio and warrants future research focusing on the reasons for their prescribing to pregnant women.