Hypertensive disorder in pregnancy is common and the optimal ultrasound surveillance of the fetus in this setting is unclear.

The aim of this study is to assess the relationship between the fetal cerebroplacental ratio (CPR) and perinatal outcomes in pregnancies complicated by maternal hypertension.

Materials and Methods
A retrospective cohort study was performed over ten years at a single centre. All women who had an ultrasound scan between 34 and 37 weeks gestation with a non‐anomalous singleton pregnancy were included. The hypertensive cohorts were compared to a non‐hypertensive cohort. Each cohort was divided into low CPR for gestational age, or normal/high CPR and these were correlated with intrapartum and perinatal outcomes.

A low CPR in a hypertensive pregnancy is associated with an increased risk of induction of labour, emergency caesarean section and poor perinatal outcome. This significance persists when adjusted for gestational age and birth weight. The diagnosis of pre‐eclampsia combined with a low CPR markedly increases the risk of poor perinatal outcome, with 52.6% (P < 0.001) of fetuses in this group having either neonatal intensive care unit admission, respiratory distress, low Apgar score, or acidosis. The odds ratio of a fetus with low CPR in a woman with pre‐eclampsia having a poor composite outcome is 4.09 (95% CI: 1.85−9.06). Conclusion There is an association between low CPR and the perinatal outcomes of pregnancies complicated by a hypertensive disorder. This association appears to be stronger in pregnancies complicated by pre‐eclampsia than in other types of hypertensive disorders.