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Utility of the cerebroplacental ratio (CPR) in marijuana exposed growth restricted fetuses
Bobby K Brar1, Pooja P Brar2, Michael O Gardner2
1Department of Gynecology and Obstetrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Insights
In marijuana-exposed fetuses with FGR, an abnormal cerebroplacental ratio (CPR) identifies those at higher risk for adverse outcomes. This CPR assessment aids in predicting severe fetal growth restriction and related complications.
Area of Science:
- Perinatal medicine
- Fetal imaging
- Obstetrics
Background:
- Fetal growth restriction (FGR) increases perinatal complication risks.
- The cerebroplacental ratio (CPR) reflects fetal well-being and predicts adverse outcomes.
- Marijuana (MJ) use during pregnancy is a growing concern.
Purpose of the Study:
- To evaluate the CPR's role in identifying marijuana-exposed FGR fetuses at increased risk.
- To assess the association between abnormal CPR and adverse perinatal outcomes in this population.
Main Methods:
- Retrospective cohort study of 192 high-risk singleton pregnancies over 4 years.
- Isolated self-identified daily MJ users with third-trimester FGR.
- Calculated fetal biometry, amniotic fluid indices, and CPR; abnormal CPR defined as <1.
Main Results:
- 13.5% of MJ-exposed fetuses had FGR; 46% of these had an abnormal CPR (mean 0.60 vs. 1.57).
- Abnormal CPR was linked to lower estimated fetal weight percentile (3.33 vs. 7.64) and more severe FGR.
- Abnormal CPR correlated with oligohydramnios and abnormal umbilical artery Doppler studies.
Conclusions:
- Nearly half of MJ-exposed FGR fetuses exhibited an abnormal CPR.
- Abnormal CPR identified a subset with severe FGR, absent/reversed end-diastolic flow, and oligohydramnios.
- Abnormal CPR is a valuable tool for identifying high-risk MJ-exposed FGR fetuses.
Objective:
Fetal growth restriction (FGR) is associated with an increased risk of adverse perinatal outcomes. The cerebroplacental ratio (CPR) represents the interaction of alterations in blood flow to the fetal brain and placenta. CPR has been utilized as a superior reflection of fetal hypoxia/acidemia and therefore a better predictor of fetal morbidity. We sought to determine the role of the CPR as an adjunctive tool to identify fetuses at increased risk of adverse perinatal outcomes in a study population of marijuana (MJ) exposed FGR fetuses.
Methods:
This was a retrospective cohort study of high-risk singleton pregnancies over a 4-year period. Self-identified daily MJ users with FGR fetuses in the 3rd trimester were isolated. Fetal biometry, amniotic fluid indices, and CPRs were calculated. A CPR <1 was considered abnormal. FGR fetuses with normal and abnormal CPRs were then compared.
Results:
26/192 (13.5%) of MJ exposed fetuses were diagnosed with FGR in the 3rd trimester. 12/26 (46%) had an abnormal CPR and 14 had a normal CPR (mean CPR 0.60 vs 1.57, p = .0001). The mean EFW percentile was lower in the abnormal CPR group in comparison to the group with normal CPR (3.33 vs 7.64, p = .0001). Both groups showed evidence of brain sparing with an overall mean head circumference of 17.55 in comparison to a mean abdominal circumference of 5.63. A CPR <1 was associated with more severe FGR, oligohydramnios, and abnormal UA Doppler studies.
Conclusions:
Approximately half of the MJ exposed FGR fetuses had an abnormal CPR. In this subset of patients, >90% had severe FGR, a higher proportion had absence/reversal of end diastolic flow in the UA, and a higher proportion had oligohydramnios. This demonstrates that an abnormal CPR identifies a group of FGR fetuses at a greater risk of adverse perinatal outcomes.
