Increasing obstetric intervention for fetal growth restriction is shifting birthweight centiles: a retrospective cohort study

Objective To assess the impact of increasing obstetric intervention on birthweight centiles. Design Retrospective cohort study of births in five 2‐year epochs: 1983–84, 1993–94, 2003–2004, 2013–2014 and 2016–2017. Population 665 205 singleton births at ≥32 weeks' gestation. Setting All maternity services in Victoria, Australia. Methods For each epoch, we calculated the birthweight cutoffs defining each birthweight centile at 34, 37 and 40 weeks' gestation. We calculated rates of iatrogenic delivery over time. We then calculated the number of babies whose birthweight would have classified them as ≥3rd centile based on 1983–84 centile definitions but as