Utility of Head/Abdomen Circumference Ratio in the Evaluation of Severe Early-Onset Intrauterine Growth Restriction

Objective: To determine whether the predominant phenotype of intrauterine growth restriction (IUGR) is symmetric or asymmetric in severe, early-onset disease due to placental insufficiency. Methods: We conducted a retrospective chart review of high-risk pregnant women with severe, early-onset IUGR who were delivering at < 33+0 weeks' gestation at Mount Sinai Hospital from 2001 to 2010. Ultrasound images were reviewed for fetal biometry, amniotic fluid volume, and uterine and umbilical Doppler flow studies within seven days of delivery, and the frequency of head circumference/abdominal circumference ratio ≥ 95th percentile for gestation was determined. Results: Sixty-two of 107 pregnancies (58%) with early-onset IUGR had an elevated HC/AC ratio (≥. 95th percentile), which was more than 10-fold greater than the expected proportion (P < 0.001). High rates of severe preeclampsia (53%), abnormal amniotic fluid (70%), and abnormal uterine artery Doppler studies (78%) indicated placental insufficiency. Conclusion: Fetuses with severe placental IUGR in the second trimester are more likely to have an asymmetric phenotype. This is in contrast to the current belief that asymmetric IUGR is confined to third trimester IUGR.