Pain medications during pregnancy: data from the Japan environment and children's study

Analgesic medication epidemic during pregnancy is an important issue in Western countries. However, no large epidemiological study involving pregnant women with pain and their medication use has been conducted in Japan. This study examined the current situation of medication use for non-cancer pain during the perinatal period in Japan using national cohort data.

We analyzed 94,649 pregnant women who completed a self-report questionnaire investigating bodily pain and an interview-based medication use survey. Medication use before and during pregnancy and new medication administration/discontinuation during pregnancy were compared between women with and without pain during pregnancy using multivariable covariance analysis.

Mild pain was reported by 50.4% of pregnant women in the first trimester (survey 1) and 61.8% in the second/third trimester (survey 2). Moderate-to-severe pain was reported by 15.4% of women in survey 1 and 22.4% in survey 2. In survey 1, 6.2% of women used prescribed analgesics and 1.6% used over-the-counter analgesics. In survey 2, prescribed and over the counter analgesics were used by 12.2% and 0.8% of women, respectively. Other pain-related medications were rarely used (< 1.0%). Pregnant women with moderate-to-severe pain showed a lower proportion of discontinuation of analgesics and a higher proportion of new administration of prescription and transdermal analgesics compared with those without pain.

Although a large proportion of pregnant women experience pain, medication use for pain during pregnancy is low in Japan compared with Western countries (50-60%). Adequate treatment or support may be necessary for pregnant women experiencing pain in Japan.