P1-297 Maternal characteristics in relation to low birth weight infants in a Japanese cohort study

Introduction A low birth weight (LBW) is an important indicator of infant morbidity and mortality. There is also growing evidence that the adverse consequences of LBW may continue throughout a subject9s life. The aim of this study was to determine the association of maternal factors during pre-pregnancy and pregnancy with LBW in a Japanese population. Methods A prospective cohort study carried out in Tokyo by the National Center for Child Health and Development of Japan was performed between 1 October 2003 and 31 December 2005. A total of 1338 pregnant women with singleton pregnancies were recruited at ≦16 weeks gestation and followed-up until partus. Logistic regression models were used to assess the risk factors for LBW. Results A maternal age of 30–34 years (OR=2.83, 95% CI 1.17 to 6.88), an increase in maternal height in cm (OR=0.94, 95% CI 0.89 to 0.99), pre-pregnancy body mass index 2 (OR=2.53, 95% CI 1.47 to 4.34), gestational weight gain during pregnancy Conclusions Our findings suggest that higher maternal socio-economic status, passive exposure to smoking early in pregnancy, pre-pregnancy thinness and insufficient weight gain during pregnancy are important predisposing factors for LBW, and a history of oral ferrotherapy to treat anaemia seems to decrease the risk of LBW.