Recent trends in the prevalence of and factors associated with maternal smoking during pregnancy in Japan

Aim: To compare the prevalence of maternal smoking during pregnancy and the correlations between maternal smoking and other maternal lifestyle or pregnancy factors between the years 1996-2001 and 2001-2006. Methods: The participants were pregnant women who responded to questionnaires while registering their pregnancies between 1 April 1996 and 31 March 2001 (Group 1), and between 1 April 2001 and 31 March 2006 (Group 2). The odds ratios were calculated with a 95% confidence interval for maternal smoking during early pregnancy by using a logistic multivariate regression analysis based on maternal factors. Results: In Group 1, 1051 pregnant women responded to the questionnaire administered at pregnancy registration, and 86 (8.2%) mothers reported smoking during early pregnancy. In Group 2, 1022 pregnant women responded, and 91 (8.9%) mothers reported smoking during early pregnancy. There was no significant difference between the groups. In both groups, partner smoking and skipping breakfast were significantly associated with maternal smoking. In Group 2, unintended pregnancy was significantly associated with maternal smoking. Conclusions: To prevent maternal smoking during pregnancy, it is necessary to carefully monitor pregnant women who report partner smoking, skipping breakfast, and unintended pregnancy.