Heated tobacco product use and hypertensive disorders of pregnancy and low birth weight: analysis of a cross-sectional, web-based survey in Japan

OBJECTIVES: Knowledge on the impact of heated tobacco product (HTP) use in pregnant women with associated maternal and neonatal risks for hypertensive disorders of pregnancy (HDP) and low birth weight (LBW) is limited. We aimed to assess the status of HTP use among pregnant women in Japan and explore the association of HTP use with HDP and LBW. DESIGN: Cross-sectional study. SETTING: Data from the Japan 'COVID-19 and Society' Internet Survey study, a web-based nationwide survey. PARTICIPANTS: We investigated 558 postdelivery and 365 currently pregnant women in October 2020. PRIMARY AND SECONDARY OUTCOME MEASURES: Information on HDP and LBW was collected from the postdelivery women's Maternal and Child Health Handbooks (maternal and newborn records). We estimated the age-adjusted ORs and 95% CIs of ever HTP smokers for HDP and LBW and compared them with those of never HTP smokers in a logistic regression analysis. RESULTS: The prevalence of ever and current HTP use were 11.7% and 2.7% in postdelivery women and 12.6% and 1.1% in currently pregnant women, respectively. Among currently pregnant women who were former combustible cigarette smokers, 4.4% (4/91) were current HTP smokers. Among postdelivery women, ever HTP smokers had a higher HDP incidence (13.8% vs 6.5%, p=0.03; age-adjusted OR=2.48, 95% CI 1.11 to 5.53) and higher LBW incidence (18.5% vs 8.9%, p=0.02; age-adjusted OR=2.36, 95% CI 1.16 to 4.87). CONCLUSIONS: In Japan, the incidence of ever HTP use exceeded 10% among pregnant women, and HTP smoking may be associated with maternal and neonatal risks.