Faculty Bibliography

OBJECTIVE:To examine the patterns and predictors of third-degree and fourth-degree laceration in women undergoing vaginal delivery. METHODS:We identified a population-based cohort of women in the United States who underwent a vaginal delivery between 1998 and 2010 using the Nationwide Inpatient Sample. Multivariable log-linear regression models were developed to account for patient, obstetric, and hospital factors related to lacerations. Between-hospital variability of laceration rates was calculated using generalized log-linear mixed models. RESULTS:Among 7,096,056 women who underwent vaginal delivery in 3,070 hospitals, 3.3% (n=232,762) had a third-degree laceration and 1.1% (n=76,347) had a fourth-degree laceration. In an adjusted model for fourth-degree lacerations, important risk factors included shoulder dystocia and forceps and vacuum deliveries with and without episiotomy. Other demographic, obstetric, medical, and hospital variables, although statistically significant, were not major determinants of lacerations. Risk factors in a multivariable model for third-degree lacerations were similar to those in the fourth-degree model. Regression analysis of hospital rates (n=3,070) of lacerations demonstrated limited between-hospital variation. CONCLUSION/CONCLUSIONS:Risk of third-degree and fourth-degree laceration was most strongly related to operative delivery and shoulder dystocia. Between-hospital variation was limited. Given these findings and that the most modifiable practice related to lacerations would be reduction in operative vaginal deliveries (and a possible increase in cesarean delivery), third-degree and fourth-degree laceration rates may be a quality metric of limited utility.

OBJECTIVE:Research on immediate neonatal resuscitation suggests that maternal magnesium exposure may be associated with increased risk of low Apgar scores, hypotonia, and neonatal intensive care unit admission. However, not all studies support these associations. Our objective was to determine whether exposure to magnesium at the time of delivery affects initial neonatal resuscitation. STUDY DESIGN/METHODS:This is a secondary analysis of the Randomized Controlled Trial of Magnesium Sulfate for the Prevention of Cerebral Palsy that evaluated whether the study drug (magnesium or placebo) that was administered at the time of delivery was associated with increased risk for a composite adverse neonatal resuscitation outcome (5-minute Apgar score <7, oxygen administration in the delivery room, intubation, chest compressions, hypotension, and hypotonicity). A subgroup analysis was performed among patients who delivered at ≥30 weeks of gestation. Log-linear regression was used to control for possible confounders. RESULTS:Data for 1047 patients were analyzed, of whom 461 neonates (44%) were exposed to magnesium. There was no increased risk for the primary composite outcome associated with magnesium exposure. Individual adverse neonatal outcomes and other secondary short-term neonatal outcomes that were evaluated also did not demonstrate an association with magnesium exposure. CONCLUSION/CONCLUSIONS:Exposure to magnesium sulfate did not affect neonatal resuscitation or other short-term outcomes. These findings may be useful in planning neonatal care and patient counseling.

OBJECTIVE:The objective of the study was to determine whether risk of recurrent preterm birth differs based on the clinical presentation of a prior spontaneous preterm birth (SPTB): advanced cervical dilatation (ACD), preterm premature rupture of membranes (PPROM), or preterm labor (PTL). STUDY DESIGN/METHODS:This retrospective cohort study included singleton pregnancies from 2009 to 2014 complicated by a history of prior SPTB. Women were categorized based on the clinical presentation of their prior preterm delivery as having ACD, PPROM, or PTL. Risks for sonographic short cervical length and recurrent SPTB were compared between women based on the clinical presentation of their prior preterm birth. Log-linear regression was used to control for confounders. RESULTS:Of 522 patients included in this study, 96 (18.4%) had prior ACD, 246 (47.1%) had prior PPROM, and 180 (34.5%) had prior PTL. Recurrent PTB occurred in 55.2% of patients with a history of ACD compared with 27.2% of those with PPROM and 32.2% with PTL (P = .001). The mean gestational age at delivery was significantly lower for those with a history of ACD (34.0 weeks) compared with women with prior PPROM (37.2 weeks) or PTL (37.0 weeks) (P = .001). The lowest mean cervical length prior to 24 weeks was significantly shorter in patients with a history of advanced cervical dilation when compared with the other clinical presentations. CONCLUSION/CONCLUSIONS:Patients with a history of ACD are at an increased risk of having recurrent preterm birth and cervical shortening in a subsequent pregnancy compared with women with prior preterm birth associated PPROM or PTL.

OBJECTIVE:To characterize the use of cervical cerclage on a population basis. METHODS:This population-based study of U.S. natality records from 2005 to 2012 evaluated use of cerclage in singleton and multiple gestation live births. Obstetric, medical, and demographic characteristics were evaluated. A multivariable logistic regression model was developed to determine factors associated with cerclage. Sensitivity analyses were performed to evaluate cerclage placement in multiple gestations. RESULTS:A total of 21,312,920 pregnancies including 71,582 women who underwent cerclage were included in the analysis. The overall rate of cerclage ranged between 0.3% and 0.4% during the study period. Multiple gestation was a leading characteristic associated with cerclage with 0.3% of singleton pregnancies, 1.3% of twins, 7.9% of triplets, and 18.0% of higher-order pregnancies undergoing the procedure. Another leading characteristic associated with cerclage included prior preterm birth (2.4%). In multivariate regression analyses, these factors retained significance. Cerclage use based on specific risk factors did not change appreciably during the study period. CONCLUSION/CONCLUSIONS:Cerclage is a commonly performed obstetric procedure that was used in similar clinical scenarios over the course of the study period. Although research evidence is less supportive of cerclage use in particular high-risk groups such as multiple gestations, these findings have not been translated into clinical practice. These findings underscore the importance of society guidelines and other tools to encourage best clinical practices.

This article reviews evidence and recommendations for maternal early warning systems designed to reduce severe maternal morbidity and mortality. The clinical rationale for these systems is discussed as is research literature on early warning systems from other fields.

OBJECTIVE:To determine the test characteristics of transabdominal ultrasonography as a screening test for second-trimester placenta previa. METHODS:This secondary analysis of a prospective cohort study evaluated the distance from the placental edge to the internal os (placenta-cervix distance) through both transabdominal and transvaginal ultrasonography during the anatomic survey. Patients were recruited in the Maternal-Fetal Medicine Ultrasound Unit at the Hospital of the University of Pennsylvania, an urban tertiary care center. Transabdominal placenta-cervix distance cutoffs with high sensitivity for detection of previa and low-lying placenta were identified, and test characteristics were calculated. Follow-up ultrasound data, pregnancy, and delivery outcomes for those with second-trimester previa or low-lying placenta were obtained. RESULTS:One thousand two hundred fourteen women were included in the analysis. A transabdominal placenta-cervix distance cutoff of 4.2 cm was 93.3% sensitive and 76.7% specific for detection of previa with a 99.8% negative predictive value at a screen-positive rate of 25.0%. A cutoff of 2.8 cm was 86.7% sensitive and 90.5% specific with a 99.6% negative predictive value at a screen-positive rate of 11.4%. Only 9.8% (four of 41) of previas and low-lying placentas persisted through delivery. CONCLUSION/CONCLUSIONS:Transabdominal ultrasonography is an effective screening test for second-trimester placenta previa. At centers not performing universal transvaginal ultrasonography at the time of the anatomic survey, evidence-based transabdominal placenta-cervix distance cutoffs can optimize the identification of patients who require further surveillance for previa.

Preeclampsia, intrauterine growth restriction, and placental abruption are serious obstetrical complications that constitute the syndrome of ischemic placental disease and account for a disproportionate degree of perinatal morbidity and mortality. We review the risks of stillbirth and neonatal and infant mortality in relation to ischemic placental disease, focusing on population-based studies. We also review the risks of neonatal morbidity and neurodevelopmental outcomes in relation to ischemic placental disease. A synthesis of the findings of the relevant studies relating ischemic placental disease to adverse perinatal outcomes underscores two important observations. First, despite the low prevalence of each of the three obstetrical complications, all are associated with increased risks of adverse perinatal and infant outcomes, as well as neurodevelopmental deficits. Second, the burden of increased perinatal risks appears strongest during the preterm period. Efforts to reduce the risks of ischemic placental disease remain critically important and developing effective clinical interventions will be a target worthy for consideration.