Antihypertensives prescribed for pregnant women in Japan: Prevalence and timing determined from a database of health insurance claims

Purpose The purpose of the study is to evaluate the status of prescribed antihypertensives primarily during pregnancy, but also before pregnancy and after delivery, using a large claims database in Japan. Methods The dates of pregnancy onset and delivery were identified using reported algorithms and the birth months of infants. The prevalence and timing of prescribed antihypertensives during pregnancy were descriptively evaluated. Time trends in prescriptions were evaluated using multivariate logistic regression analyses. We also evaluated the prevalence of antihypertensives prescribed within 180 days before pregnancy and 180 days after delivery among women who were covered by health insurers during the entire period. Results At least one antihypertensive agent was prescribed for 1144 (2.74%) of 41 693 pregnant women. The most frequently prescribed oral antihypertensive during pregnancy was nifedipine, followed by methyldopa, hydralazine, and furosemide. Drugs targeting the renin-angiotensin system were prescribed for 21 pregnant women (0.05%), including angiotensin II receptor blockers that were prescribed for 19 (0.05%) of them. Nicardipine was the most frequently prescribed injectable antihypertensive during pregnancy, followed by furosemide, hydralazine, and nitroglycerin. Annual prescription trends remained similar except for a significant decrease in those for oral and injectable furosemide and an annual increase in those for organic nitrate. Based on an evaluation of 33 941 pregnant women, the number of prescriptions for antihypertensives increased particularly during the third trimester, then decreased from 91 to 180 days after delivery. Conclusions Various types of antihypertensives are prescribed for Japanese pregnant women. The effects of exposing pregnant Japanese women to these agents should be evaluated.