Objective: The majority of intrapartum fetal hypoxia occurs in uncomplicated pregnancies. Current intrapartum monitoring techniques have not resulted in a reduction in the incidence of cerebral palsy in term neonates. We report the development of a composite risk score to allow risk stratification of normal pregnancies before labor.
Methods: Six hundred one women were recruited to this prospective observational study. All women underwent an ultrasound examination before active labor, during which fetal biometry and fetal Doppler flow resistance indices were measured. A composite risk score, amalgamating data from the umbilical artery, middle cerebral artery, and umbilical vein, was then developed and correlated with intrapartum outcomes.
Results: In cases with the highest composite risk scores, the incidence of fetal compromise (the primary outcome) was 80.0% compared with just 15.3% in cases with the lowest risk scores (relative risk 5.2, 95% confidence interval 2.7-10.1). These cases were also at increased risk of cesarean delivery (53.3% compared with 3.4%, P<.001) and of developing a fetal heart rate pattern considered pathologic by National Institute for Health and Clinical Excellence criteria (P=.003). No significant variation in Apgar scores or umbilical artery pH was observed.
Conclusion: Intrapartum fetal compromise remains a significant global health issue. The composite risk score reported here can identify fetuses at both high risk and low risk of a subsequent diagnosis of intrapartum fetal compromise. This may enable more judicious use of current intrapartum fetal monitoring techniques, which are hampered by low specificity.
Level of evidence: II.