The April issue of Ultrasound in Obstetrics & Gynecology includes a series of papers on cerebroplacental ratio values and their use in the management of labor. Articles on other topics include a Randomized Controlled Trial on the association between Cesarean hysterotomy level and large uterine scars, a Systematic Review on delivery or expectant management for prevention of adverse maternal and neonatal outcomes in hypertensive disorders of pregnancy, and studies on the contribution of maternal factors and growth velocity in predicting a small-for-gestational-age neonate and whether phenotype of a previous preterm birth should influence the management of a subsequent pregnancy in women with a short cervix.
The cerebroplacental ratio: normal values and management of labor
Studies in both small- (SGA) and appropriate-for-gestational-age fetuses have reported associations between low cerebroplacental ratio (CPR), due to decreased middle cerebral artery (MCA) pulsatility index (PI) and/or increased uterine artery (UA) PI, and adverse perinatal outcome. In a Systematic Review, Oros et al. evaluated the methodological quality criteria of studies reporting reference ranges for CPR and Doppler indices of UA and MCA, finding considerable methodological heterogeneity (download the accompanying Journal Club slides). While Oros et al. suggest the inclusion of complicated pregnancies as putting a study at high risk of bias, Ciobanu et al. developed Fetal Medicine Foundation reference ranges for UA-PI and MCA-PI and CPR without exclusion of such pregnancies, which allowed for evaluation of maternal characteristics and medical history that affect UA-PI, MCA-PI and CPR. Maternal age, body mass index, racial origin, method of conception, smoking and parity were found to have a significant effect on these measurements.
As poor performance of CPR for adverse perinatal outcome in previous studies may be attributable to the adverse event at term being too remote from the gestational age at which CPR was assessed, Fiolna et al. investigated whether this performance is improved by undertaking the assessment within 24 hours prior to induction of labor. CPR was found to be associated with increased risk of Cesarean section for fetal distress and adverse neonatal outcome, but the performance of CPR for such surrogate measures of fetal hypoxic morbidity is poor. Dall’Asta et al. evaluated the relationship between CPR measured in early labor and perinatal and delivery outcomes in a cohort of uncomplicated singleton term pregnancies. It was found that, while reduced CPR is associated with a higher risk of obstetric intervention due to fetal distress and composite adverse perinatal outcome, it is a poor predictor of adverse perinatal outcome.
Also included in this issue…
Hysterotomy level at Cesarean section and occurrence of large scar defects: a randomized single-blind trial
An association between large scar defects in non-pregnant women and uterine rupture/dehiscence of scar in a subsequent delivery has been suggested. In this Randomized Controlled Trial, Vikhareva et al. assessed the association between the level of Cesarean hysterotomy and the presence of a large uterine scar defect detected by transvaginal ultrasound examination 6–9 months after delivery. Low hysterotomy level in women in advanced labor was found to be associated with a higher incidence of a large scar defect.
Delivery or expectant management for prevention of adverse maternal and neonatal outcomes in hypertensive disorders of pregnancy: an individual participant data meta-analysis
In hypertensive disorders of pregnancy, delayed delivery carries maternal risks, while early delivery increases fetal risk, and optimal timing of delivery remains unclear. In this Systematic Review, Bernardes et al. compared immediate delivery to expectant monitoring for prevention of adverse maternal and neonatal outcomes in pregnancies from 34 weeks of gestation complicated by a hypertensive disorder, finding that immediate delivery reduces the risk of maternal complications, while the effect on the neonate depends on gestational age.
Prediction of small-for-gestational-age neonates at 35–37 weeks’ gestation: contribution of maternal factors and growth velocity between 20 and 36 weeks
Prenatal detection of a SGA neonate can reduce the risk of perinatal mortality. Ciobanu et al. evaluated estimated fetal weight (EFW) at 35 + 0 to 36 + 6 weeks’ gestation in the prediction of delivery of a SGA neonate and the additive value of maternal factors and fetal growth velocity between 20 and 36 weeks. EFW was found to predict 63% of SGA neonates, which was not improved by the addition of growth velocity, and prediction of 90% of SGA neonates necessitates classification of about 35% of the population as being screen positive.
Should phenotype of previous preterm birth influence management of women with short cervix in subsequent pregnancy? Comparison of vaginal progesterone and Arabin pessary
There is increasing evidence that spontaneous preterm birth (sPTB) with intact membranes at labor and preterm prelabor rupture of membranes (PPROM) have distinct biological pathways. Care et al. investigated whether the classification of a previous sPTB impacts the efficacy of cervical pessary or vaginal progesterone for prevention of sPTB in women with short cervix. It was found that cervical pessary may be less efficacious in women with previous PPROM, and the authors suggest that classification of a previous PTB should be reported in future clinical trials.
Coming up in the next issue of UOG…
- A Randomized Controlled Trial on the impact of exercise during pregnancy on maternal weight gain and fetal cardiac function. Read the EarlyView article.
- A Systematic Review on variation in outcome reporting in randomized controlled trials of interventions for prevention and treatment of fetal growth restriction. Read the EarlyView article.