Does Gestational Age Misclassification Explain the Difference in Birthweights for Australian Aborigines and Whites?
International Journal of Epidemiology 1996; 25: 980 988. BACKGROUND: After 34 weeks gestation, summary measures of location for birthweight (e.g. means and centiles) increase more slowly for Australian Aborigines than for whites. A similar pattern has been observed for blacks in the US. This study tests whether the reported pattern is due to differential misclassification of gestational age. METHODS: Simulation was used to measure the potential effect of differential misclassification of gestational age. Reported gestational age data were obtained from Queensland Perinatal Data Collection (QPDC), Estimates of the true distributions of gestational age were obtained by assuming various (plausible) types of misclassification and applying these to the reported distributions. Previous studies and data from the QPDC were used to help specify the birthweight distributions used in the simulations. RESULTS: At full term, the parameters of the birthweight distributions were robust to gestational
