Correlation of maternal body mass index with umbilical artery Doppler in pregnancies complicated by fetal growth restriction and associated outcomes

Objective: To evaluate the correlation between umbilical artery (UA) Doppler and its feasibility across categories of maternal body mass index (BMI; calculated as weight in kilograms divided by the square of height in meters) in the presence of fetal growth restriction (FGR).

Methods: A total of 1074 singleton pregnancies with suspected FGR on ultrasound examination between 24+0 and 36+0 weeks of pregnancy were reviewed. Evaluation of the UA Doppler was performed at 1- to 2-weekly intervals. Abnormal UA Doppler findings and delivery outcomes were compared between the different maternal BMI categories.

Results: Increased UA pulsatility index (PI >95th centile) was reported in 81% of obese class II patients (BMI 35-39.9) compared with a 46% incidence in the remaining categories, normal (BMI <24.9), overweight (BMI 25-29.9), and obese class I (BMI 30-34.9) (P = 0.001). In absent or reversed end diastolic flow (AEDF/REDF) we found an increasing incidence across the BMI categories (4%-25%) (P < 0.001). Higher maternal BMI was associated with lower birthweights and higher cesarean section rates. Increasing maternal BMI did not affect successful assessment of UA Doppler.

Conclusion: There is a positive correlation between increasing maternal BMI and abnormal UA Doppler findings in FGR. Maternal BMI may be considered as an additional risk factor when evaluating UA Doppler for placental insufficiency.