Cardiovascular transition to extrauterine life in growth-restricted neonates: relationship with prenatal Doppler findings.
OBJECTIVE
Cardiovascular status in fetal growth restriction (FGR) can be classified by the severity of individual Doppler abnormalities (early and late) or by the rate of clinical progression. We tested the hypothesis that aspects of the fetal cardiovascular status in FGR affect neonatal cardiovascular findings.


STUDY DESIGN
FGR cases [abdominal circumference <5th percentile and an elevated umbilical (MCA) artery (UA) pulsatility index] had UA, middle cerebral artery and ductus venosus (DV) Doppler. Positive UA end-diastolic velocity and/or a low MCA pulsatility index denoted early and absent/reversed UA end-diastolic velocity, whereas an increased DV pulsatility index for veins denoted late responses. The rate of progression was classified into mild, progressive and severe. After delivery, shunt dynamics and blood flow across the patent ductus arteriosus (PDA), foramen ovale and atriaventricular valves, myocardial contractility and pharmacologic pressor requirement were noted at neonatal echocardiography. These findings were related to prenatal Doppler parameters.


RESULTS
In 94 patients, only individual Doppler parameters related to neonatal echocardiographic findings. Absent/reversed UA DV significantly predicted PDA with right to left shunt (p = 0.016). The pressor need for cardiovascular instability was observed in neonates with abnormal prenatal DV Doppler and with lower birth weights delivered at earlier gestational age (p < 0.0001 for both). Pressor need was significantly related to neonatal death (Nagelkerke R² = 0.35, p = 0.002).


CONCLUSION
A markedly abnormal UA Doppler predisposes growth-restricted neonates to persistence of fetal circulation associated with right to left shunting. Abnormal venous Doppler is a risk factor for cardiovascular instability which in turn significantly contributes to neonatal mortality. Further clarification of the neonatal cardiovascular transition may be helpful in guiding early neonatal assessment and management.