Risk of Expectant Management and Optimal Timing of Delivery in Low-Risk Term Pregnancies: A Population-Based Study.

OBJECTIVE: The benefits of the 39-week rule have been questioned and concerns of increased stillbirth after adoption of this rule have been raised. Whether expectant management risks outweigh the benefits of awaiting 39 weeks has not been studied. We analyze the risks of expectant management at term and the optimal timing for delivery. STUDY DESIGN: All U.S. nonanomalous singleton term deliveries in 2013 were selected, excluding diabetes/hypertension, and low birth weight. Maternal/neonatal complications and stillbirth/infant death were compared among expectant management versus deliveries at each term gestational age. Logistic regression was used to calculate adjust odds ratios of complications according to delivery plan at each gestational age. RESULTS: From approximately 3 million deliveries, maternal complications during expectant management were lower at early term, and became higher at 39 weeks, relative risk [RR] (95% confidence interval [CI]) = 1.18 (1.16-1.19). Neonatal complications during expectant management were lower during early term, and became higher at ≥39 weeks, RR (95% CI) = 1.09 (1.08-1.09). The risk of perinatal mortality in the expectant management group was lower during early term, and became higher at ≥39 weeks, 18.93 (17.83-20.10) versus 17.37 (16.61-18.16), p = 0.010. CONCLUSION: Complications during expectant management occurring while awaiting full term do not outweigh the benefits of better outcomes from reaching 39 weeks. However, extending beyond 39 weeks may put these pregnancies at an increased risk.

Contemporary epidemiology and novel predictors of uterine rupture: a nationwide population-based study.

PURPOSE: In spite of several policies aiming to decrease cesarean rates and related complications such as uterine rupture, data show that uterine rupture and associated morbidity are increasing along the years. Whether previously unidentified risk factors are currently playing an important role on these trends is unknown. We analyze current risks of uterine rupture and main preceding factors from more recent years compared to former data. METHODS: All uterine rupture cases in the US from 2011-2012 were selected, with matched non-uterine rupture cases selected as controls. Variables considered for analysis included demographics, maternal morbidity, and obstetric complications. Likelihood forward selection was used to identify main risk factors of uterine rupture. Medians of main factors identified were used to simulate groups at risk and calculate odds ratios of uterine rupture. RESULTS: From ~8 million births, 1925 presented uterine rupture. In patients with no prior cesarean delivery, multiple gestation, chronic hypertension and chorioamnionitis presented the highest odds of uterine rupture, with the combination of these factors increasing the odds of rupture 59 times (~1%). In women with prior cesarean delivery, induction/augmentation and chorioamnionitis were the most significant predictors, with the combination increasing the odds 33 times (~3%). CONCLUSIONS: Despite policies implemented and changes in clinical practice, uterine rupture remains an important issue. Previously unidentified risk factors are playing now an important role, information that should be considered during patient counseling and clinical practice. Combinations of some of these factors may increase the risk of uterine rupture significantly enough to modify clinical care.