Trends in prescription of pregnancy-contraindicated drugs in Korea, 2007-2011

This study aims to evaluate changes in use of contraindicated drugs during pregnancy in Korea using the nationwide Health Insurance and Assessment Service (HIRA) database. Study drugs were 314 drugs that were announced as pregnancy-contraindicated on December 11, 2008. The study population consisted of the pregnant women who gave birth and were prescribed any of the drugs in 2007-2011 before giving birth. Pregnancy-contraindicated drug use was defined as the proportion of prescriptions among pregnant women that were for study drugs. The relative and absolute reductions in contraindicated drug use after the 2008 action were estimated with 95% confidence interval (CI) by medical institution type, region, and drug class. The predicted monthly contraindicated drug use was estimated by performing ordinary least-squares regression analysis of data before the action and compared with observed data after the action. Between 2007 and 2011, a total of 1,468,588 pregnant women received 1,796,208 prescriptions. Contraindicated drug use accounted for 15.96% of total prescriptions (N = 355,783) before the action but decreased to 11.52% (N = 453,832) afterward. Overall, the relative reduction was 27.77% (95% CI: 27.64%-27.90%) and greatest for hormones at 46.56% (95% CI: 46.21%-46.93%). The relative reduction was 55.43% (95% CI: 54.60%-55.43%) for all category X drugs, 17.09% (95% CI: 16.46%-17.75%) for category X drugs excluding hormones, and 0.14% (95% CI: 0.14%-0.15%) for category D drugs including hormones. A regulatory action toward pregnancy-contraindicated drugs led to moderate decrease in contraindicated drug use during pregnancy. Despite the decreases, contraindicated drugs were still widely prescribed to pregnant women, highlighting the need to develop strategies to assess and improve drug safety during pregnancy.