Association of the Cerebro-Placental Ratio With Adverse Outcomes in Pregnancies Affected by Gestational Diabetes Mellitus

Objectives: Cerebro-placental ratio (CPR) is a doppler tool contributes to clinical decision-making in pregnancies affected by small for gestational age weight (SGA). Pregnancies affected by gestational diabetes mellitus (GDM) tend to have higher newborn weight, but greater risk of adverse perinatal outcomes. We hypothesized that in GDM-complicated-pregnancies CPR will be associated with adverse perinatal outcomes even in the absence of SGA. Methods: This prospective single-center cohort study included non-anomalous singleton pregnancies in women with GDM. Those with pre-pregnancy diabetes mellitus, hypertensive disorder or suspected SGA were excluded. Routine fetal sonographic assessment included CPR—defined as middle cerebral artery pulsatilty index/umbilical artery pulsatilty index. Masked CPR measurement closest to birth was used, classified as >10th (normal) or ≤10th centile (low). Primary outcome was a composite, consisting of stillbirth, Caesarean birth due to abnormal fetal heart rate pattern, 5-minute Apgar <7, cord arterial pH < 7.0, hypoxic ischemic encephalopathy, or NICU admission >24 hours. Results: Of 281 participants, 24 (8.5%) had low CPR, at a mean gestational age of 36.3 weeks (IQR 34.0–37.4). Birthweight percentile was significantly lower among the low CPR group (35th [IQR 16–31] versus 60th [IQR 31–82]; P =.002). There was no statistically difference in the primary composite outcome between the groups (8.3% versus 7.0%, P =.68). Low CPR was significantly associated with a higher risk of neonatal hypoglycemia (adjusted odds ratio 3.2, 95% CI 1.2–8.3). Conclusion: In pregnancies affected by GDM, CPR ≤10th percentile was not associated with adverse perinatal outcome but was associated with neonatal hypoglycemia.