Cardiovascular severe maternal morbidity in pregnant and postpartum women: development and internal validation of risk prediction models.

OBJECTIVES: To develop and internally validate risk prediction models identifying women at risk for cardiovascular severe maternal morbidity (CSMM). DESIGN: A retrospective cohort study. SETTING: An obstetric teaching hospital between 2007 and 2017. POPULATION: A total of 89 681 delivery hospitalisations. METHODS: We created and evaluated two models, one predicting CSMM at delivery (delivery model) and the other predicting CSMM postpartum following discharge from delivery hospitalisation (postpartum CSMM). We assessed model discrimination and calibration and used bootstrapping for internal validation. MAIN OUTCOME MEASURES: Cardiovascular severe maternal morbidity comprised the following confirmed conditions: pulmonary oedema/acute heart failure, myocardial infarction, aneurysm, cardiac arrest/ventricular fibrillation, heart failure/arrest during surgery or procedure, cerebrovascular disorders, cardiogenic shock, conversion of cardiac rhythm and difficult-to-control severe hypertension. RESULTS: The delivery model contained 11 variables and 3 interaction terms. The strongest predictors were gestational hypertension, chronic hypertension, multiple gestation, cardiac lesions or valvular heart disease, maternal age ≥40 years and history of poor pregnancy outcome. The postpartum model comprised eight variables. The strongest predictors were severe pre-eclampsia, non-Hispanic Black race/ethnicity, chronic hypertension, gestational hypertension, non-severe pre-eclampsia and maternal age ≥40 years at delivery. The delivery and postpartum models had an area under the receiver operating characteristic curve of 0.87 (95% CI 0.85-0.89) and 0.85 (95% CI 0.80-0.90), respectively. Both models were adequately calibrated and performed well on internal validation. CONCLUSIONS: These tools may help providers to identify women at highest risk of CSMM and enable future prevention measures. TWEETABLE ABSTRACT: Risk assessment tools for cardiovascular severe maternal morbidity were developed and internally validated.

The effect of labour induction on the risk of caesarean delivery: using propensity scores to control confounding by indication.

OBJECTIVE: To use propensity score methods to control for confounding by indication in the association between labour induction and caesarean delivery. DESIGN: Cross-sectional analysis of administrative hospital discharge data supplemented by medical record information. SETTING: Fourteen US member hospitals of the National Perinatal Information Center. SAMPLE: A cohort of 166 559 singleton liveborn deliveries in the period 2007-2012. METHODS: We used propensity scores (PSs) to balance 83 covariates between induced and non-induced women, and compared estimates with traditional covariate adjustment. We estimated PSs for labour induction versus expectant management of pregnancy each week from 34 to 42 weeks of gestation. We estimated risk ratios (RRs) for the association between labour induction and primary caesarean delivery from models with no adjustment, traditional adjustment of five covariates, matched PS, and adjustment for continuous PS. MAIN OUTCOME MEASURE: Caesarean delivery in current or subsequent week of gestation. RESULTS: In crude models labour induction increased the risk of caesarean delivery in all weeks (RR 1.06-1.52), excepting 39 weeks of gestation (RR 0.89). After matching on PS, the analysis showed a significantly decreased risk of caesarean delivery with labour induction during weeks 35-39 (RR 0.77-0.92), and a significantly elevated risk at weeks 40 (RR 1.22) and 41 (RR 1.39). Traditional covariate and PS adjustment resulted in RRs between those from crude and PS-matched models. CONCLUSIONS: There is evidence of considerable confounding by indication in the association of labour induction and caesarean delivery, particularly for preterm deliveries. Using PS methods, we found a reduced risk of caesarean delivery with labour induction before 40 weeks of gestation, and an elevated risk for weeks 40-42. TWEETABLE ABSTRACT: With confounding adjustment, labour induction does not increase the risk of caesarean at 34-39 weeks of gestation.

Changes in delivery methods at specialty care hospitals in the United States between 2006 and 2010.

OBJECTIVE: Given the increasing rates of labor induction and cesarean delivery, and efforts to reduce early term births, we examined recent trends in methods and timing of delivery. STUDY DESIGN: We identified delivery methods and medical indications for delivery from administrative hospital discharge data for 231 691 deliveries in 2006 and 213 710 deliveries in 2010 from 47 specialty care member hospitals of the National Perinatal Information Center/Quality Analytic Services. In a subset of 17 hospitals, we examined trends by gestational age. RESULT: From 2006 to 2010, there was an 11% increase in labor induction and a 6% increase in cesarean delivery, largely due to repeat cesareans. There was a 4 per 100 reduction in early term births (37 to 38 weeks), mostly due to a decline in non-medically indicated interventional deliveries. CONCLUSION: We report a shift in deliveries at 38 weeks, which we believe may be attributed to efforts to actively limit non-medically indicated early term deliveries.