Development of a customised birthweight standard for ethnic Chinese subjects

A model to establish customised birthweight standards for the Chinese popul ation was developed, using data from a cohort of 1564 Chinese women with no rmal singleton pregnancies. Multiple regression analysis was performed usin g maternal height, weight, parity, gestation at delivery and fetal sex as i ndependent (predictor) variables. From this, a customised ideal birthweight for each baby can be estimated, and the normality of the actual birthweigh t can be evaluated according to this, rather than from population standards . The results of this study show that birthweights are strongly influenced by maternal characteristics, confirming conclusions from similar studies in o ther ethnic populations. The overall mean birthweight at 280 days of gestat ion was 3252 g, which was smaller than that of the Caucasian population. Bi rthweight increased with maternal height (5.1 g/cm), maternal booking weigh t (10.2 g/kg) and gestation at delivery (18.3 g/day from 280 days): Babies from women who had two previous deliveries weighed 145.2 g more than the nu lliparous. Male babies were 84.8 g heavier than females. Adjustment using t hese results produces a customised ideal birthweight for each baby. When compared with population based standards, customised birthweight stand ards identified significantly fewer small for gestational age (SGA - birthw eight below 10th centile, McNemar Chi square = 19.1, p < 0.01) and fewer la rge for gestational age (LGA - birthweight above 90th centile, McNemar Chi square = 23.7, p < 0.01) cases.