Factors associated with maternal smoking during early pregnancy: Relationship with low-birth-weight infants and maternal attitude toward pregnancies

Objective: Previously, we had identified negative maternal attitudes toward pregnancies and maternal smoking as independent risk factors for low-birth-weight (LBW) infants. Here, we aim to examine these relationships in a prospective cohort in Japan. Study Design: A prospective cohort and cross-sectional study Setting: Koshu City administration office and Department of Health Sciences, School of Medicine, University of Yamanashi, Japan Participants: The participants included 1,242 pregnant women who responded to our questionnaires while registering their pregnancies between January 01, 1995 and July 31, 2000. We collected infant data from 1,015 mothers (follow-up rate: 81.7%). Method: The expectant mothers responded to a questionnaire-based survey aimed at ascertaining their lifestyle habits while registering their pregnancies. Subsequently, we collected data on the infants' birth weights and gestational weeks from the records in the Maternal and Child Health Handbook. Main Outcome Measure: Odds ratio was calculated with a 95% confidence interval for LBW and maternal smoking during early pregnancy by using a logistic multivariable regression analysis based on maternal factors. Results: In this cohort, maternal smoking during early pregnancy was significantly associated with LBW. Negative maternal attitude toward pregnancies was not an independent risk factor for LBW but was significantly associated with maternal smoking during early pregnancy. Skipping breakfast just before pregnancy was also significantly associated with maternal smoking. Conclusion: Negative maternal attitude toward pregnancies was not an independent LBW risk factor but was associated with maternal smoking during pregnancy. It is important to observe maternal attitude and lifestyle for preventing LBW infants.