Pre- and postnatal brain hemodynamics in pregnancies at term: correlation with Doppler ultrasound, birthweight, and adverse perinatal outcome

Purpose: To elucidate the correlation between pre- and postnatal cerebral Doppler in pregnancies close to term and to explore whether they are associated with perinatal outcome. Materials and methods: Prospective study on singleton pregnancies at 36-37 weeks of gestation. The primary outcome was a composite score of perinatal morbidity, while secondary outcomes were adverse intra-partum outcome and abnormal acid-base status. All pregnancies underwent ultrasound assessment of umbilical artery (UA), middle cerebral artery (MCA), uterine arteries (UtAs) pulsatility index (PI), and cerebroplacental ratio (CPR). At birth, neonatal MCA PI was measured 72 h from delivery and correlated with prenatal Doppler, primary and secondary outcomes. Fisher's test and multivariate logistic regression analysis were used to analyze the data. Results: One hundred and sixty-six fetuses with both pre- and postnatal Doppler assessment of the MCA were included in the study. The risk of composite perinatal morbidity was higher in fetuses (OR: 5.7, 95% CI 2.2-14.6) and newborns (OR: 4.1, 95% CI 1.8-9.6) with fetal MCA PI < 10th centile. Likewise, the incidence of abnormal acid-base status was higher both in fetuses (20 versus 4.2%, p = .026) and newborns (17.1 versus 3.2%, p = .001) with a low MCA PI before and at birth, respectively. At logistic regression analysis, fetal and neonatal MCAPI were independently associated with composite perinatal morbidity and abnormal acid-base status, but not with adverse intra-partum outcome. In small for gestational age (SGA) fetuses, the incidence of composite perinatal morbidity was higher in fetuses and new-borns presenting compared to those not presenting with an MCA PI < 10th centile (61.5 versus 20%, p = .003 and 52.6% versus 7.1%, p = .008, respectively), while such association was lost when considering non-SGA fetuses. Conclusion: A low MCA PI is associated with adverse perinatal outcome in pregnancies at term and tends to persist after birth.