Secular trends of birthweight in a population of live-born, singletons, without congenital anomalies in Queensland, Australia

Abstract Objectives and importance Maternal and family patterns are changing, and these changes can influence birthweight. Past research and organisational reports focus on short temporal timelines or broad trends, but trends across a longer temporal period are important. The aim of this study is to assess the trends in birthweight and maternal characteristics across a 19-year period using descriptive statistics. Study type and methods Birth records (n = 1,166,055) were obtained for a 19-year period (2000–2019) and a descriptive secular trend analysis was performed. Results and conclusions Mean birthweight trended down across the study period, while rates of large for gestational age births increased. This appears to be driven by a decrease in gestational age across the period. Maternal factors, such as smoking, BMI and Indigenous status, were found to be linked with changes in mean birthweight and the proportion of small for gestational age or large for gestational age. More babies were born to older women by the end of the study period. There was a sharp rise in gestational diabetes, and more large for gestational age births to these women. Over time, the large for gestational age births started to decline, suggesting better care practices for women with gestational diabetes.