Habitual Smoking and Perinatal Outcomes in Japan

Smoking during pregnancy has been reported to increase the perinatal risk. We investigated the perinatal outcomes in Japanese pregnant women with habitual smoking at pre-pregnancy and during pregnancy who delivered at our institute in Japan.

We reviewed the obstetric records of 9280 Japanese women with singleton delivery at ≥22 weeks of gestation at our institute between 2014 and 2019. On admission for delivery, a routine face-to-face interview was conducted by our midwives to ask about smoking during pregnancy.

Of the total 9280 pregnant Japanese women, 532 (5.7%) had smoked before pregnancy. Of these, 272 (51.5%) quitted smoking after being diagnosed with pregnancy, while 258 (49.5%) continued to smoke during pregnancy and were diagnosed with habitual smoking during pregnancy. There was no significant relation between habitual smoking at pre-pregnancy and the perinatal adverse outcomes. However, habitual smoking during pregnancy was associated with the adverse perinatal outcomes such as the increased incidence of placental abruption (adjusted odds ratio [OR] 2.38, p = 0.04) and light-for-gestational-age neonate (adjusted OR 1.72, p = 0.03) on multiple logistic regression analyses.

In this study, smoking was found to be associated with the adverse perinatal outcomes. The current results support the importance of smoking cessation during pregnancy.