Maternal determinants of birth weight: a population-based sample from Qingdao, China.

This analysis examines the relationship between maternal determinants and birth weight in a population-based birth cohort of 5,284 mothers with singleton births of 28 completed gestational weeks in Qingdao, China, in 1992. Multiple linear regression models suggest that the length of the menstrual cycle, age at menarche, maternal weight, maternal height, parity, and number of antenatal visits had independent effects on birth weight after controlling for gestational age and sex of infant. The estimated difference in mean birth weight for each year after menarche was 11.7 g (95 per cent CI 4.6-18.8), and for each day of the menstrual cycle was 4.0 g (95 per cent CI, 2.1-6.0), after controlling for gestational age, sex of infant, maternal height, maternal weight, parity and the number of antenatal visits. No substantial differences in determinants of birth weight were found between the sexes. Maternal age, education, and occupation failed to reveal any significant association with birth weight. In sum, those women who reached menarche younger and had a relatively short menstrual cycle had a heavier baby on average, and the determinants of birth weight did not differ between male and female in the cohort.