The Use of Japanese Traditional (Kampo) Medicines Before and During Pregnancy in Japan: The Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study.

Purpose: Japanese traditional (Kampo) medicines are often used for pregnant women in Japan. However, no comprehensive studies have been conducted regarding the self-reported use of these medicines during pregnancy. This study investigated the use of Kampo medicines during pregnancy in Japan using the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study (TMM BirThree Cohort Study).

Methods: Questionnaires were distributed to pregnant women participating in the TMM BirThree Cohort Study (July 2013 to March 2017) at approximately 12 weeks (early pregnancy) and 26 weeks (middle pregnancy). We analysed Kampo medicines use over three periods: (1) 12 months before pregnancy diagnosis, (2) the period between pregnancy diagnosis and around Week 12 of pregnancy and (3) from around Week 12 of pregnancy.

Results: In total, 19 220 women were included in the analysis. The proportions using prescribed Kampo medicines were 4.1% before pregnancy diagnosis, 4.5% from diagnosis to Week 12% and 4.5% after Week 12 of pregnancy. The most frequently prescribed Kampo medicines were tokishakuyakusan (1.0%) before pregnancy diagnosis, shoseiryuto (1.3%) from diagnosis to Week 12 and shoseiryuto (1.5%) Post-week 12. Sixty of the pregnant women used Kampo medicines containing crude drugs, which should be administered cautiously during pregnancy.

Conclusion: The proportion of Kampo medicines use before and during pregnancy was 4%-5%. Some pregnant women used Kampo medicines containing crude drugs that should be administered cautiously during pregnancy. Further research is required to determine the safety of Kampo medicines during pregnancy.