Abstract
BACKGROUND: New tobacco products, including heated tobacco products and electronic cigarettes, are rapidly increasing in popularity among younger populations worldwide, particularly in Japan. Thus, clarifying the effects of both active and passive smoking of new tobacco products during pregnancy is an urgent public health concern. We focused on nausea and vomiting in pregnancy (NVP) which is traditionally and epidemiologically considered an indicator of healthy pregnancy progression. In this study, we classified maternal and paternal smoking status focussing on new tobacco product use and investigated its association with the absence of NVP. METHODS: This cross-sectional study used control data from a case-control study designed to explore modifiable factors for anorectal malformations. The questionnaire survey was conducted within seven Japanese regions between December 2019 and March 2023, enrolling a total of 1,522 postpartum women. The study included 1,450 postpartum women who delivered singleton babies and provided complete information. The main outcome was the absence of NVP. The exposure was the smoking status of mothers and their partners, classified into four categories: dual users (combustible cigarettes and new tobacco products), new tobacco product-only users, combustible cigarette-only users, and non-smokers (reference). Logistic regression analysis was performed to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the absence of NVP. RESULTS: Based on maternal smoking status, the absence of NVP was reported in 27.1% of dual users, 25.0% of new tobacco product-only users, 18.0% of combustible cigarette-only users, and 15.2% of non-smokers. Maternal dual use was associated with an increased OR of the absence of NVP (adjusted OR = 2.07, 95% CI: 1.02-4.22). After restricting to non-smoking mothers, the adjusted OR for paternal combustible cigarette smoking was 2.62 (95% CI: 1.25-5.50). CONCLUSION: Our main finding was the positive association between maternal dual use of new tobacco products and combustible cigarettes during pregnancy and the absence of NVP. This suggests that smoking cessation guidance during pregnancy, including new tobacco products, is particularly warranted. TRIAL REGISTRATION: Not applicable.