Reduced fetal movements and cerebroplacental ratio: evidence for worsening fetal hypoxemia.

OBJECTIVE: To investigate the fetal cerebroplacental ratio (CPR) in women presenting with reduced fetal movements (RFM).

METHODS: This was a retrospective cohort study of data collected over an 8-year period at a fetal medicine unit at a tertiary referral center. The cohort comprised 4500 singleton pregnancies presenting with RFM at or after 36 weeks' gestation and 1527 control pregnancies at a similar gestational age without RFM. Fetal biometry and Doppler parameters were recorded and converted into centiles and multiples of the median (MoM). CPR was defined as the ratio between the fetal middle cerebral artery (MCA) pulsatility index (PI) and the umbilical artery (UA) PI. Subgroup analysis for fetal size and for single vs multiple episodes of RFM was performed.

RESULTS: Compared with controls, pregnancies with RFM had lower MCA-PI MoM (median, 0.95 vs 0.97; P < 0.001) and CPR MoM (median, 0.97 vs 0.99; P = 0.018). Compared with women presenting with single episodes of RFM, pregnancies with multiple episodes (≥ 2 episodes) had lower CPR MoM (median, 0.94 vs 0.98; P = 0.003). On subgroup analysis for fetal size, compared with controls, appropriate-for-gestational-age fetuses in the RFM group had lower MCA-PI MoM (median, 0.96 vs 0.97; P = 0.003) and higher rate of CPR below the 5th centile (5.3% vs 3.6%; P = 0.015). Logistic regression analysis demonstrated an association of risk of recurrent RFM with maternal age (OR, 0.96; 95% CI, 0.93-0.99), non-Caucasian ethnicity (OR, 0.72; 95% CI, 0.53-0.97), estimated fetal weight centile (OR, 1.01; 95% CI, 1.00-1.02) and CPR MoM (OR, 0.24; 95% CI, 0.12-0.47).

CONCLUSION: Pregnancies complicated by multiple episodes of RFM show significantly lower CPR MoM and MCA-PI MoM compared with those with single episodes and controls. This is likely to be due to worsening fetal hypoxemia in women presenting with recurrent RFM. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.