Objective: To develop a model for predicting postpartum readmission for hypertension and pre-eclampsia at delivery discharge and assess external validation or model transportability across clinical sites.Design: Prediction model using data available in the electronic health record from two clinical sites.Setting: Two tertiary care health systems from the Southern (2014-2015) and Northeastern USA (2017-2019).Population: A total of 28 201 postpartum individuals: 10 100 in the South and 18 101 in the Northeast.Methods: An internal-external cross validation (IECV) approach was used to assess external validation or model transportability across the two sites. In IECV, data from each health system were first used to develop and internally validate a prediction model; each model was then externally validated using the other health system. Models were fit using penalised logistic regression, and accuracy was estimated using discrimination (concordance index), calibration curves and decision curves. Internal validation was performed using bootstrapping with bias-corrected performance measures. Decision curve analysis was used to display potential cut points where the model provided net benefit for clinical decision-making.Main outcome measures: The outcome was postpartum readmission for either hypertension or pre-eclampsiaResults: The postpartum readmission rate for hypertension and pre-eclampsia overall was 0.9% (0.3% and 1.2% by site, respectively). The final model included six variables: age, parity, maximum postpartum diastolic blood pressure, birthweight, pre-eclampsia before discharge and delivery mode (and interaction between pre-eclampsia x delivery mode). Discrimination was adequate at both health systems on internal validation (c-statistic South: 0.88; 95% confidence interval [CI] 0.87-0.89; Northeast: 0.74; 95% CI 0.74-0.74). In IECV, discrimination was inconsistent across sites, with improved discrimination for the Northeastern model on the Southern cohort (c-statistic 0.61 and 0.86, respectively), but calibration was not adequate. Next, model updating was performed using the combined dataset to develop a new model. This final model had adequate discrimination (c-statistic: 0.80, 95% CI 0.80-0.80), moderate calibration (intercept -0.153, slope 0.960, E-max 0.042) and provided superior net benefit at clinical decision-making thresholds between 1% and 7% for interventions preventing readmission. An online calculator is provided here.Conclusions: Postpartum readmission for hypertension and pre-eclampsia may be accurately predicted but further model validation is needed. Model updating using data from multiple sites will be needed before use across clinical settings.

BackgroundSecond trimester pregnancy induction with misoprostol in women with prior caesarean delivery is not well studied.ObjectiveTo estimate the risk of uterine rupture using misoprostol as an induction agent for pregnancy termination in the second trimester of pregnancy in women with prior caesarean delivery.Search strategyCases of women with a history of prior caesarean delivery and subsequent misoprostol induction for pregnancy termination in the second trimester (16-28 weeks) were obtained from two main data sources. First, a retrospective chart analysis was performed at Thomas Jefferson University Hospital and Christiana Hospital between 1998 and 2004. Second, multiple Medline, Scopus and POPLINE literature searches were performed.Selection criteriaCase series and cohort studies of women with one or more prior caesarean delivery (of any type), and with a subsequent pregnancy with induction of labour for pregnancy termination at 16-28 weeks using misoprostol as the initial primary agent were included. Case reports were analysed separately.Data collection and analysisTotal cases were analysed by type and number of prior caesarean delivery, for the primary outcome of uterine rupture.Main resultsThe incidence of uterine rupture associated with second trimester misoprostol termination was 0.4% (2/461) in women with one prior low transverse, 0% (0/46) in those with two prior low transverse and 50% (1/2) in those with a prior classical caesarean delivery. One of the cases of uterine rupture in a woman with a prior low transverse caesarean required transfusion. None of the total eight cases (including case reports) of uterine rupture was associated with hysterectomy.ConclusionsSecond trimester misoprostol termination appears safe among women with one prior low transverse caesarean birth, as it is associated with incidences of uterine rupture of 0.4% (95% confidence interval 0.08-1.67%), of hysterectomy of 0% and of transfusion of 0.2%. There are insufficient data on risk with more than one prior caesarean birth or with prior classical caesarean birth.