To compare birth weights in central Sydney to the INTERGROWTH21st international standard to describe current trends in relation to optimal growth and to define areas that may benefit from improved obstetric surveillance and intervention.

Retrospective analysis of prospectively collected cohort. Design: hospital‐based cohort study. Setting: Sydney Local Health District, Australia. Population or sample: women with singleton pregnancies who had first trimester screening for aneuploidy between 16 April, 2010 and 9 March, 2012. Analysis of 2966 births. Main outcome measures: Large for gestational age (LGA) >4000 g, >4500 g, >5000 g, >90th, >95th, >97th centiles and small for gestational age (SGA) <1500 g, <2500 g,