Does the Cerebroplacental Ratio (CPR) Predict Adverse Outcomes in Low Risk Pregnancies?

This is a multicenter prospective study of low-risk nulliparous women who will be recruited
if they are having an ultrasound at 36 weeks of estimated gestational age or greater. As part
of the study, women will have umbilical and middle cerebral artery Doppler studies and the
CPR will be calculated by dividing the middle cerebral artery PI by the umbilical artery PI.
Providers caring for study subjects will be blinded to this result. Pregnancy outcomes in
women with CPR values less than the 10th percentile for gestational age will be compared to
those with CPR values above the 10th percentile.

A secondary aim of the study is to analyze CPR as a continuous variable.

Inclusion Criteria:

- Nulliparous pregnant women between the ages of 18 and 45 years with low risk
pregnancies who present for obstetrical ultrasound at 36 weeks of gestation or later
with a planned delivery at a Perinatal Research Consortium hospital.

Exclusion Criteria:

- Multifetal pregnancy at the time of presentation

- Known fetal chromosomal anomaly

- Known fetal malformation

- Preeclampsia

- Fetal growth restriction

- Multiparity

- Prior cesarean section

- Placental abnormalities such as previa or accreta

- Pregestational diabetes

- Plan to deliver outside the Perinatal Research Consortium affiliated hospitals