Abstract

STUDY OBJECTIVE--The aim was to investigate the effect of passive smoke exposure during pregnancy on fetal growth in the Japanese population. DESIGN--The study comprised a community based interview and clinical survey of pregnant women in Aichi Prefecture, Japan. SETTING--Participants attended for delivery at 146 private and public practices and hospital clinics in the Prefecture. SUBJECTS--Participants were 6831 women who delivered a live singleton without malformation during the three consecutive months from June 1987, and comprised about 34% of total deliveries in the Prefecture during the period. MEASUREMENTS AND MAIN RESULTS--35% of the women had been exposed passively to cigarette smoke for 2 h or more per day at home, in the work place, or in other places during pregnancy. At this level of passive exposure among non-smoking women with term deliveries (greater than or equal to 37 weeks), a small effect on fetal growth was observed; mean birth weight was reduced by 10.8 g, and the relative risk of growth retardation (less than 2500 g birth weight) was 1.0 (95% CI: 0.7-1.5), after adjusting age, parity, height, alcohol drinking, occupation, and gestation. CONCLUSIONS--The results suggest that the reduction of fetal growth associated with passive smoke exposure during pregnancy may be small in Japanese population.