Toshiyuki Ojima

The purpose of this study is to quantify the population attributable fraction of active and passive smoking for low birth weight in Japan. A population-based case-control study was conducted by mailing self-report questionnaires. The cases were all singleton low birth weight babies who were born between 1 January 1998 and 30 June 1999 in Tochigi prefecture, Japan. The controls were randomly selected from all singleton babies who were born during the same period as cases in the prefecture. The number of cases and controls were 286 and 404, respectively. Population attributable fractions of active smoking during and before pregnancy were 7.0% and 8.8%, respectively. Population attributable fraction of passive smoking at home was 15.6% and at the workplace was 1.1%. Combined population attributable fraction of both active and passive smoking was 17.3%. Public education to eliminate passive smoking for pregnant women and smoking prevention in adolescence is very important in order to reduce the risk of low birth weight.