MATERNAL MENSTRUAL HISTORY AND SMALL-FOR-GESTATIONAL-AGE BIRTHS IN A POPULATION-BASED CHINESE BIRTH COHORT

The relationship between maternal menstrual history and small-for-gest ational-age (SGA) births is examined in a population-based birth cohor t of 5291 mothers with singleton births and 28 completed gestational w eeks in Qingdao, China, in 1992. Multivariate analyses suggest that th e length of the menstrual cycle and age at menarche had independent ef fects on SGA after controlling for sex of the infant, physical size of the mother, blood pressure at the first antenatal visit, parity, gest ational week at the first antenatal visit, number of antenatal visits, number of previous spontaneous abortions and maternal educational att ainment and occupation. The relative risk (RR) of SGA among thin mothe rs (BMI < = 21) is 1.63 (95% confidence interval (CI) 1.16-2.29) if th e mother's menarche started after 14 years (reference to < = 14 years) , 1.75 (95% CI 0.96-3.20) if the mother's menstrual cycle was 29-30 da ys and 2.92 (95% CI 1.42-6.03) if the menstrual cycle > = 31 days (< = 28 as a reference category for both). Among normal weight mothers (BM I 21-24), only a menstrual cycle equal or longer than 31 days still ha d a significant effect on SGA (RR 2.17, 95% CI 1.18-4.08), and among f at mothers no significant effects were observed. The results encourage further evaluation of the association between maternal menstrual back ground and fetal development among other ethnic populations and explor ation of the possible biological mechanisms behind this relationship. (C) 1997 Elsevier Science Ireland Ltd.