Postpartum readmission for hypertension and pre-eclampsia: development and validation of a predictive model

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-eclampsia <6 weeks after delivery.

RESULTS

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 × 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, Emax 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.

Association of Neighborhood Socioeconomic Disadvantage and Postpartum Readmission

We assessed whether neighborhood socioeconomic disadvantage, as measured by the Area Deprivation Index (ADI), was associated with an increased risk of postpartum readmission. This is a secondary analysis from nuMoM2b (Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-To-Be), a prospective cohort of nulliparous pregnant individuals from 2010 to 2013. The exposure was the ADI in quartiles, and the outcome was postpartum readmission; Poisson regression was used. Among 9,061 assessed individuals, 154 (1.7%) were readmitted postpartum within 2 weeks of delivery. Individuals living with the most neighborhood deprivation (ADI quartile 4) were at increased risk of postpartum readmission compared with those living with the lowest neighborhood deprivation (ADI quartile 1) (adjusted risk ratio 1.80, 95% CI 1.11-2.93). Measures of community-level adverse social determinants of health, such as the ADI, may inform postpartum care after delivery discharge.

Optimal predelivery hemoglobin to reduce transfusion and adverse perinatal outcomes

BACKGROUND

Maternal anemia has been associated with poor obstetrical outcomes; however, the optimal hemoglobin level for reducing blood transfusion at delivery has not been well-defined.

OBJECTIVE

This study aimed to measure the association of maternal anemia immediately before delivery with peripartum transfusion and other adverse perinatal outcomes. We also sought to identify the optimal hemoglobin level for predicting transfusion.

STUDY DESIGN

This was a retrospective cohort study of patients who had hemoglobin or hematocrit collected before delivery of live, nonanomalous neonates at ≥23 weeks' gestation at a single center (2013-2018). Patients were excluded if they had sickle cell disease or were receiving anticoagulation. Patients were categorized as having anemia or no anemia on the basis of predelivery hemoglobin or hematocrit levels using criteria set by the American College of Obstetricians and Gynecologists. The primary outcome was transfusion of ≥1 unit of packed red blood cells during the delivery admission. Secondary outcomes included select adverse perinatal outcomes. Bivariable analyses compared baseline characteristics and outcomes between the anemia and no-anemia groups. Multivariable logistic regression estimated the association between anemia and outcomes. The hemoglobin cutoff optimizing sensitivity and specificity for transfusion was identified by the Liu method.

RESULTS

Of the 18,357 patients included in the analysis, 5444 (30%) had predelivery anemia (mean hemoglobin, 10.0±0.8 g/dL) vs 12,913 (70%) who did not (mean hemoglobin, 12.3±1.1 g/dL). Patients with anemia were more likely to be non-Hispanic Black and publicly insured and less likely to be nulliparous. Anemia was associated with 5-fold higher odds of packed red blood cell transfusion (6.0% vs 1.3%; adjusted odds ratio, 5.23 [95% confidence interval, 4.09-6.69]) compared with no anemia. For each 1 g/dL increase in predelivery hemoglobin, the odds of transfusion were 56% lower (adjusted odds ratio, 0.44 [confidence interval, 0.40-0.48]). The optimal hemoglobin for prediction of transfusion was 10.6 g/dL (sensitivity: 80%, specificity: 86%). There was no association between anemia and composite maternal or neonatal morbidity after adjustment for covariates, but anemia was associated with higher odds of postpartum readmission (adjusted odds ratio, 1.35 [1.11-1.64]).

CONCLUSION

Maternal anemia before delivery was associated with 5-fold higher odds of packed red blood cell transfusion and postpartum readmission, but not other perinatal morbidity. Optimizing predelivery hemoglobin, particularly ≥10.6 g/dL, may reduce peripartum transfusion.

Participation in obstetrical studies is associated with improved pregnancy outcomes

BACKGROUND

The association between pregnant patients participating in obstetrical studies and pregnancy outcomes is understudied.

OBJECTIVE

This study aimed to evaluate the association between participation in obstetrical studies and maternal and neonatal outcomes.

STUDY DESIGN

This was a retrospective cohort study of all patients delivering at a single center from 2013 to 2018. Patients with pregnancy loss at <13 weeks of gestation or major fetal anomalies were excluded. Patients who enrolled in one or more obstetrical studies were categorized as "study participants" and were compared with patients who did not enroll in an obstetrical study, that is, "study nonparticipants." The primary outcome was a composite of maternal morbidity diagnosed up to 6 weeks after delivery. The secondary outcomes included composite neonatal morbidity and other perinatal outcomes. Bivariate analyses compared baseline demographics and outcomes between groups. Multivariable logistic regression was used to estimate adjusted odds ratios with 95% confidence intervals. Subgroup analyses by study design (trial or observational) were planned.

RESULTS

Of 19,569 patients included in this analysis, 3848 (19.7%) were study participants, and 15,721 (80.3%) were study nonparticipants. Among study participants, 3023 (78.6%) enrolled in a trial, and 825 (21.4%) enrolled in an observational study. The study participants had higher body mass index and were more likely to be younger, non-Hispanic Black, publicly insured, nulliparous, and undergo cesarean delivery than study nonparticipants. Compared with study nonparticipants, the study participants had significantly lower odds of composite maternal morbidity (9.2% vs 8.7%; adjusted odds ratio, 0.83; 95% confidence interval, 0.73-0.95) and composite neonatal morbidity (27.5% vs 18.6%; adjusted odds ratio, 0.53; 95% confidence interval, 0.48-0.58). In addition, the odds of fetal death, 5-minute Apgar score of <5, neonatal death, maternal and neonatal intensive care unit admissions, and lengths of stay were lower for study participants than for study nonparticipants. In stratified analyses, maternal morbidity was only significantly decreased among trial participants; however, there was a significantly reduced odds of neonatal morbidity, regardless of study design (trial or observational vs no study).

CONCLUSION

Participation in obstetrical studies was associated with decreased maternal and neonatal morbidities after adjusting for potential confounders. This underscored the importance of pregnant patients enrolling in obstetrical clinical studies and potentially benefiting from the additional surveillance. Further study of how study participation exerts this effect on pregnancy outcomes is warranted.

Postpartum Hospital Readmissions and Emergency Department Visits Among High-Risk, Medicaid-Insured Women in New York City

Objectives: To describe the incidence of and characteristics associated with postpartum emergency department (ED) visits and hospital readmissions among high-risk, low-income, predominantly Black and Latina women in New York City (NYC). Methods: We conducted a secondary analysis of detailed survey and medical chart data from an intervention to improve timely postpartum visits among Medicaid-insured, high-risk women in NYC from 2015 to 2016. Among 380 women who completed surveys at baseline (bedside postpartum) and 3 weeks after delivery, we examined the incidence of having an ED visit or readmission within 3 weeks postpartum. We used logistic regression to examine unadjusted and adjusted associations between patient demographic, clinical, and psychosocial characteristics and the odds of postpartum hospital use. Results: In total, 12.8% (n = 48) of women reported an ED visit or readmission within 3 weeks postpartum. Unadjusted odds of postpartum hospital use were higher among women who self-identified as Black versus Latina, U.S. born versus foreign born, and English versus Spanish speaking. Clinical and psychosocial characteristics associated with increased unadjusted odds of postpartum hospital use included cesarean delivery, hypertensive disorders of pregnancy, and positive depression or anxiety screen, and we found preliminary evidence of decreased hospital use among women breastfeeding at three weeks postpartum. The odds of seeking postpartum hospital care remained roughly 2.5 times higher among women with hypertension or depression/anxiety in adjusted analyses. Conclusions: We identified characteristics associated with ED visits and hospital readmissions among a high-risk subset of postpartum women in NYC. These characteristics, including depressive symptoms and hypertension, suggest women who may benefit from additional postpartum support to prevent maternal complications and reduce health disparities.

Association between peripartum hysterectomy and venous thromboembolism

BACKGROUND

The risk of venous thromboembolism after delivery is modified by mode of delivery, with the risk of venous thromboembolism being higher after cesarean delivery than vaginal delivery. The risk of venous thromboembolism after peripartum hysterectomy is largely unknown.

OBJECTIVE

This study aimed to compare the incidence and risk of venous thromboembolism among women who had and did not have a peripartum hysterectomy. Furthermore, we sought to compare the risk of venous thromboembolism after hysterectomy with other patient, pregnancy, and delivery risk factors known to be associated with venous thromboembolism.

STUDY DESIGN

This was a cross-sectional study of women with delivery encounters identified in the Nationwide Readmissions Database from October 2015 to December 2017. Delivery encounters and all variables of interest were identified using the International Classification of Diseases, Tenth Revision diagnosis and procedure codes. The incidence of venous thromboembolism during delivery and rehospitalizations within 6 weeks after discharge was compared among women who had and did not have a peripartum hysterectomy. Multivariable logistic regressions were used to estimate associations between venous thromboembolism and hysterectomy, adjusted for the following characteristics: maternal age, payer at time of delivery, obesity, hypertension, diabetes mellitus, tobacco use, multifetal gestation, peripartum infection, and peripartum hemorrhage. Similarly, venous thromboembolism risk was compared by mode of delivery, including hysterectomy. Diagnoses that may have been indications for peripartum hysterectomy were identified among patients who underwent a hysterectomy and compared between those who did and did not have venous thromboembolism. Analyses used survey weights to obtain population estimates.

RESULTS

Of the 4,419,037 women with deliveries, 5098 (11.5 per 10,000 deliveries) underwent a hysterectomy. Moreover, 110 patients (215.8 per 10,000 deliveries) were diagnosed with venous thromboembolism after hysterectomy. The risk of venous thromboembolism was significantly higher in women who underwent a hysterectomy than in women who did not have a hysterectomy (unadjusted odds ratio, 25.1 [95% confidence interval, 20.0-31.5]; adjusted odds ratio, 11.2 [95% confidence interval, 8.7-14.5]; P<.001). Comparing the risk of venous thromboembolism by mode of delivery, the unadjusted and adjusted incidences of venous thromboembolism were 6.9 (95% confidence interval, 6.5-7.3) and 7.4 (95% confidence interval, 6.9-7.8) per 10,000 deliveries among women after vaginal delivery without peripartum hysterectomy, 12.5 (95% confidence interval, 11.8-13.1) and 11.3 (95% confidence interval, 10.7-12.0) per 10,000 deliveries after cesarean delivery without hysterectomy; and 217.2 (95% confidence interval, 169.1-265.2) and 96.9 (95% confidence interval 76.9-126.5) per 10,000 deliveries after hysterectomy, regardless of mode of delivery. Of the 110 diagnoses of venous thromboembolism with peripartum hysterectomy, 89 (81%) occurred during delivery admission. Of the remaining 21 cases, 50% occurred within the first 10 days after discharge from delivery, and 75% occurred within 25 days after discharge.

CONCLUSION

These findings have demonstrated that peripartum hysterectomy is associated with a markedly increased risk of venous thromboembolism in the postpartum period, even when controlling for other known risk factors for postpartum thromboembolic events. Here, the incidence of venous thromboembolism after peripartum hysterectomy (2.2%) met some guideline-based risk thresholds for routine thromboprophylaxis, potentially for at least 2 weeks after delivery. Further investigation into the role of routine venous thromboembolism prophylaxis during and after delivery is needed.

Severe maternal morbidity at delivery and postpartum readmission in the United States

BACKGROUND

Little is known about the extent to which severe maternal morbidity (SMM) at delivery impacts early and late postpartum readmission.

OBJECTIVES

We examined readmission rates for women with and without SMM (and their 18 subtypes) at delivery and characterised the most common medical reasons for readmissions.

METHODS

We conducted a retrospective cohort study utilising the 2016-2017 Nationwide Readmissions Database among women giving births in the United States. Deliveries were classified according to the presence or absence of 18 SMM indicators defined by the Centers for Disease Control and Prevention using the International Classification of Diseases, Tenth Edition, Clinical Modification (ICD-10-CM) diagnosis and procedure codes. The primary outcome of this study was all-cause early (≤7 day) and late (8 to 42 day) postpartum readmission. Survey-weighted Poisson regression with robust error variance was used to generate adjusted risk ratios (RR) and 95% confidence intervals (CI) to investigate the association between SMM and early and late postpartum readmission. Additionally, we compared principal diagnoses codes during readmission hospitalisations among women with and without SMM at delivery.

RESULTS

Of the 6 193 852 women examined, 4.9% (n = 4928) with any SMM and 1.4% (n = 83 995) with no SMM were readmitted within 42 days after delivery. After adjusting for obstetric co-morbidities and sociodemographic factors, women with any SMM were 57% (RR 1.57, 95% CI 1.47, 1.67) more likely to have an early readmission and 69% (RR 1.69, 95% CI 1.57, 1.82) more likely to have a late readmission compared to women with no SMM at delivery. However, the risk was attenuated when excluding women with blood transfusion only. Women with and without SMM were readmitted predominantly for obstetric complications and infections.

CONCLUSIONS

Women with SMM at delivery were more likely to experience both early and late postpartum readmission, independent of their obstetrical co-morbidity burden and sociodemographic factors.

Maternal Health after Stillbirth: Postpartum Hospital Readmission in California

OBJECTIVE

The aim of this study is to assess whether the risk of postpartum readmission within 6 weeks of giving birth differs for women who had stillbirths compared with live births.

STUDY DESIGN

Using data from the Office of Statewide Health Planning and Development in California, we performed a population-based cohort study of 7,398,640 births between 1999 and 2011. We identified diagnoses and procedures associated with the first postpartum hospital readmission that occurred within 6 weeks after giving birth. We used log-binomial models to estimate relative risk (RR) of postpartum readmission for women who had stillbirth compared with live birth deliveries, adjusting for maternal demographic, prepregnancy, pregnancy, and delivery characteristics.

RESULTS

The rate of postpartum readmission was higher among women who had stillbirths compared with women who had live births (206 and 96 per 10,000 births, respectively). After adjusting for maternal demographic and medical characteristics, the risk of postpartum readmission for women who had stillbirths was nearly 1.5 times greater (adjusted RR = 1.47, 95% confidence interval: 1.35-1.60) compared with live births. Among women with stillbirths, the most common indications at readmission were uterine infection or pelvic inflammatory disease, psychiatric conditions, hypertensive disorder, and urinary tract infection.

CONCLUSION

Based on our findings, women who have stillbirths are at higher risk of postpartum readmissions within 6 weeks of giving birth than women who have live births. Women who have stillbirths may benefit from additional monitoring and counseling after hospital discharge for potential postpartum medical and psychiatric complications.

KEY POINTS

· Women who have stillbirths are at nearly 1.5 times greater risk of postpartum readmission than women who have live births.. · Uterine infections and pelvic inflammatory disease, and psychiatric conditions are the most common reasons for readmission among women who had a stillbirth.. · Women who have stillbirths may benefit from additional monitoring and counseling after hospital discharge for potential postpartum medical and psychiatric complications..

Factors associated with postpartum readmission for hypertensive disorders of pregnancy

BACKGROUND

Postpartum readmission has negative implications for patients and health systems. Previous studies suggest that up to 5% of women with hypertensive disorders of pregnancy experience postpartum readmission. Studies examining factors associated with postpartum readmission for hypertension have had small sample sizes and conflicting results.

OBJECTIVE

This study aimed to characterize the incidence of and risk factors for postpartum readmission for hypertensive disorders of pregnancy among a cohort of women with preexisting hypertensive disorders of pregnancy.

STUDY DESIGN

This was a retrospective cohort study of pregnant women with known hypertensive disorders of pregnancy who delivered live births in a large managed care organization in 2018. The primary outcome was hospital readmission for a hypertensive diagnosis or stroke within 42 days after delivery. The primary exposure of interest was persistent postpartum hypertension, defined as a maximum systolic blood pressure of ≥140 mm Hg or maximum diastolic blood pressure of ≥90 mm Hg within 24 hours before discharge from delivery hospitalization. Continuous and categorical variables were compared using bivariate analysis. Risk factors independently associated with postpartum readmission were identified using multivariable logistic regression.

RESULTS

Of 42,022 women who delivered in 2018, 7151 had hypertensive disorders of pregnancy-an incidence of 17%. The rate of postpartum readmission among women with hypertensive disorders of pregnancy was 4.43% (317 of 7151). The following risk factors were associated with increased odds of postpartum readmission in women with hypertensive disorders of pregnancy: systolic blood pressure of ≥140 mm Hg within 24 hours before discharge (adjusted odds ratio, 2.29; 95% confidence interval, 1.71-3.07), diastolic blood pressure of ≥90 mm Hg within 24 hours before discharge (adjusted odds ratio, 1.33; 95% confidence interval, 1.02-1.73), maternal age of ≥30 years (30-34: adjusted odds ratio, 1.57; 95% confidence interval, 1.12-2.19; 35-39: adjusted odds ratio, 2.36; 95% confidence interval, 1.70-3.28; ≥40: adjusted odds ratio, 2.95; 95% confidence interval, 1.95-4.46), receipt of magnesium sulfate (adjusted odds ratio, 1.47; 95% confidence interval, 1.11-1.94), and receipt of inpatient rapid-acting antihypertensive medication (adjusted odds ratio, 1.46; 95% confidence interval, 1.10-1.93). In addition, 1 blood pressure of ≥140/90 mm Hg within 24 hours before discharge increased the odds of readmission (adjusted odds ratio, 1.98; 95% confidence interval, 1.37-2.87). Furthermore, 2 or more elevated blood pressure values further increased the odds (adjusted odds ratio, 3.14; 95% confidence interval, 2.33-4.24). Median postpartum day of readmission was day 5 (interquartile range=3).

CONCLUSION

Hospital readmission for postpartum hypertension was associated with persistent postpartum hypertension (blood pressure of ≥140/90 mm Hg), increasing maternal age, and more severe antepartum hypertension. Women with these characteristics may be targeted in future quality initiatives to mitigate readmission.

Risk factors for postpartum readmission among women after having a stillbirth

BACKGROUND

Compared to women with a live birth, women with a stillbirth are more likely to have maternal complications during pregnancy and at birth, but risk factors related to their postpartum health are uncertain.

OBJECTIVE

This study aimed to identify patient-level risk factors for postpartum hospital readmission among women after having a stillbirth.

STUDY DESIGN

This was a population-based cohort study of 29,654 women with a stillbirth in California from 1997 to 2011. Using logistic regression models, we examined the association of maternal patient-level factors with postpartum readmission among women after a stillbirth within 6 weeks of hospital discharge and between 6 weeks and 9 months after delivery.

RESULTS

Within 6 weeks after a stillbirth, 642 women (2.2%) had a postpartum readmission. Risk factors for postpartum readmission after a stillbirth were severe maternal morbidity excluding transfusion (adjusted odds ratio, 3.02; 95% confidence interval, 2.28-4.00), transfusion at delivery but no other indication of severe maternal morbidity (adjusted odds ratio, 1.95; 95% confidence interval, 1.35-2.81), gestational hypertension or preeclampsia (adjusted odds ratio, 1.93; 95% confidence interval, 1.54-2.42), prepregnancy hypertension (adjusted odds ratio, 1.80; 95% confidence interval, 1.36-2.37), diabetes mellitus (adjusted odds ratio, 1.78; 95% confidence interval, 1.33-2.37), antenatal hospitalization (adjusted odds ratio, 1.78; 95% confidence interval, 1.43-2.21), cesarean delivery (adjusted odds ratio, 1.73; 95% confidence interval, 1.43-2.21), long length of stay in the hospital after delivery (>2 days for vaginal delivery and >4 days for cesarean delivery) (adjusted odds ratio, 1.59; 95% confidence interval, 1.33-1.89), non-Hispanic black race and ethnicity (adjusted odds ratio, 1.38; 95% confidence interval, 1.08-1.76), and having less than a high school education (adjusted odds ratio, 1.35; 95% confidence interval, 1.02-1.80). From 6 weeks to 9 months, 1169 women (3.90%) had a postpartum readmission; significantly associated risk factors were largely similar to those for earlier readmission.

CONCLUSION

Women with comorbidities, with birth-related complications, of non-Hispanic black race and ethnicity, or with less education had increased odds of postpartum readmission after having a stillbirth, highlighting the importance of continued care for these women after discharge from the hospital.

Consequences of the COVID-19 pandemic on the postpartum course: Lessons learnt from a large-scale comparative study in a teaching hospital

Objective

To evaluate the consequences of COVID‐19 pandemic restrictions on the postpartum course.

Methods

A retrospective cross‐sectional study compared women who gave birth between March and April 2020 (first wave), between July to September 2020 (second wave), and a matched historical cohort throughout 2017–2019 (groups A, B, and C, respectively). Primary outcomes were postpartum length of stay (LOS), presentations to the emergency department (ED), and readmissions 30 days or longer after discharge. Following Bonferroni correction, p < 0.016 was considered statistically significant.

Results

In total, 3377 women were included: 640, 914, and 1823 in groups A, B, and C, respectively. LOS after birth (both vaginal and cesarean) was shorter in groups A and B compared to the control group (2.28 ± 1.01 and 2.25 ± 0.93 vs 2.55 ± 1.10 days, p < 0.001). Rates of ED presentations 30 days after discharge were higher in groups C and B compared to group A (6.63% and 6.45% vs 3.12%, p = 0.006). Rates of readmissions 30 days after discharge were 0.78%, 1.42%, and 1.09% (groups A, B, and C, respectively), demonstrating no statistical difference (p = 0.408).

Conclusion

During the COVID‐19 pandemic, there was a reduction or no change in rates of ED presentations and readmissions, despite the shortened LOS after delivery. A shift in policy regarding the postpartum LOS could be considered.

Length of stay after delivery was shortened during the COVID‐19 pandemic without a surge in postpartum presentations to the emergency department or rates of readmission.

Risk factors for postpartum readmission for preeclampsia or hypertension before delivery discharge among low-risk women: a case-control study

BACKGROUND

Postpartum hypertension or preeclampsia is one of the most frequent reasons for readmission after delivery discharge, and risk factors for readmission remain poorly characterized.

OBJECTIVE

This study aimed to determine risk factors of postpartum readmission for hypertension or preeclampsia among low-risk women before delivery discharge.

STUDY DESIGN

We conducted a nested case-control study from 2012 to 2015 at a tertiary care medical center. Cases were identified using diagnostic codes for postpartum transient hypertension, mild preeclampsia, severe preeclampsia, eclampsia, superimposed preeclampsia, and unspecified hypertension and readmission within 6 weeks of delivery. Controls not readmitted for hypertension or preeclampsia were time matched within 4 weeks of the delivery date to each case. We fit multivariable logistic regression models to identify independent risk factors for postpartum readmission for hypertension or preeclampsia and then calculated a receiver operating characteristic curve of the final model to assess model discrimination.

RESULTS

Within the source cohort resulting in 58 cases and 232 matched controls, the rate of postpartum readmission for preeclampsia or hypertension was 0.4% (n=58 of 14,503). The median time to readmission was 6 days (range, 2-15 days), and 40% of cases had an outpatient postpartum visit before readmission. In multivariable analysis, non-Hispanic black race (adjusted odds ratio, 2.14; 95% confidence interval, 0.99-4.59), gestational hypertension (adjusted odds ratio, 2.70; 95% confidence interval, 1.12-6.54), preeclampsia during delivery admission (adjusted odds ratio, 3.12; 95% confidence interval, 1.29-7.50), and maximum postpartum systolic blood pressure during delivery admission (adjusted odds ratio, 1.05; 95% confidence interval, 1.03-1.08) were risk factors for readmission. This model had a good discriminative ability to predict women who would require readmission for preeclampsia or hypertension (area under the curve, 0.83; 95% confidence interval, 0.74-0.89). Using these 4 factors to illustrate this model, the predicted risk of readmission ranged from <1% in the lowest risk scenario (eg, postpartum systolic blood pressure of 120 mm Hg + no hypertensive disorders of pregnancy + white race) to 26% in the highest risk scenario (eg, postpartum systolic blood pressure of 160 mm Hg + preeclampsia + black race).

CONCLUSION

Risk factors of postpartum readmission for hypertension or preeclampsia can be identified at the time of delivery discharge among low-risk women, regardless of an antenatal hypertensive disorder. A next step could be using these risk factors to develop a predictive model to guide postpartum care.

Risk factors for re-presentation for postpartum hypertension in patients without a history of hypertension or preeclampsia

BACKGROUND

Re-presentation for evaluation of hypertension following discharge after delivery is common. However, a subset of patients who re-present for evaluation of postpartum hypertension do not have a history of hypertension. Identification of those at risk may help guide postpartum management and prevent re-presentations to the hospital.

OBJECTIVE

This study aimed to establish risk factors for re-presentation for hypertension within 30 days of discharge after delivery in patients without a history of hypertension compared with women who did not re-present and to distinguish from risk factors for re-presentation for another reason.

STUDY DESIGN

Subjects were identified through data extraction from a single institution between January 2012 and December 2018. We included subjects without an International Classification of Diseases, Ninth Revision or International Classification of Diseases, Tenth Revision code for (1) chronic hypertension or (2) a hypertensive disorder of pregnancy during their delivery encounter who re-presented to the hospital within 30 days. Thus, the re-presentation group was divided into the following 2 groups: those who re-presented for hypertension and those who re-presented for any other reason. Each re-presentation group was compared with the cohort of patients who delivered within the study window and did not re-present using the Student t test or Wilcoxon tests for continuous variables and chi-square or Fisher's exact tests for categorical variables. Multivariable regression was also performed on all potentially important risk factors.

RESULTS

Factors that emerged as uniquely significant in the re-presentation group for hypertension were maternal age of ≥40 years and antenatal prescription of low-dose aspirin. Black race and body mass index of ≥30 kg/m², although significant in both re-presentation groups, were more strongly predictive of re-presentation for hypertension. These factors remained independently significant when compared with each other in a multivariable analysis.

CONCLUSION

There are identifiable risk factors for postpartum re-presentation for hypertension in patients without a history of hypertension. Upon discharge, providers may consider close blood pressure monitoring and follow-up in patients who have any of the following risk factors: age of ≥40 years, black race, body mass index of ≥30 kg/m², or those who were prescribed low-dose aspirin in pregnancy.

Institutional prevalence of class III obesity modifies risk of adverse obstetrical outcomes

BACKGROUND

Women with prepregnancy class III obesity (body mass index ≥40 kg/m²) are at an increased risk of perinatal complications and adverse obstetrical outcomes. Estimates of the magnitude of risk that these women face vary widely, which may reflect differences in institutional experience caring for women with obesity.

OBJECTIVE

We sought to characterize the relationship between institutional prevalence of prepregnancy class III obesity and the risk of adverse perinatal outcomes among these women, hypothesizing that higher-prevalence institutions would have lower rates of adverse maternal and perinatal outcomes among this population.

STUDY DESIGN

We conducted a retrospective cohort study using chart-abstracted data on births in Washington state from Jan. 1, 2012, to Dec. 31, 2017. The analysis was restricted to hospitals that delivered at least 1 patient per month with prepregnancy class III obesity. Institutional prevalence of prepregnancy class III obesity was calculated, and hospitals were classified as either high or low prevalence. We included nulliparous women with vertex-presenting singleton pregnancies at ≥37 weeks of gestation. We excluded births with missing initial body mass index. The primary outcome was the incidence of cesarean delivery. Secondary outcomes were induction of labor, postpartum complications, postpartum readmission, and neonatal intensive care unit admissions. We compared outcomes between women with prepregnancy class III and all obesity at high- and low-prevalence hospitals using the χ² test or the Fishers exact test as appropriate. Binary logistic regression was performed to compare outcomes at high- and low-prevalence hospitals. A hospital-adjusted multivariable regression model that controlled for baseline institutional rates of each outcome and compared outcomes between high- and low-prevalence hospitals was developed. A final multivariable logistic regression that controlled for both baseline institutional variation as well as potential clinical confounders was performed.

RESULTS

A total of 20,556 women at 6 hospitals were eligible for inclusion; the prevalence of prepregnancy class III obesity was 6.2% and 2.1% in high- and low-prevalence hospitals, respectively. Obese women, including those with class III obesity in a high-prevalence hospital, were more likely to be Latina and less likely to be of advanced maternal age and carry private insurance. After adjusting for the institutional cesarean delivery rate, women with prepregnancy class III obesity had significantly increased odds of cesarean delivery (odds ratio, 1.53, 95% confidence interval, 1.12-2.10); however, after adjusting for significant covariates, the association no longer achieved significance (odds ratio, 1.68, 95% confidence interval, 0.97-2.94). The hospital-adjusted odds of postpartum readmission were significantly increased for women with prepregnancy class III obesity when delivering in low-prevalence institutions (odds ratio, 6.61, 95% confidence interval, 1.93-22.56), and the association was further strengthened after controlling for significant covariates (odds ratio, 15.20, 95% confidence interval, 2.32-99.53). None of the models demonstrated significantly different odds of induction of labor, postpartum complications, or neonatal intensive care unit admission by institutional prevalence of prepregnancy class III obesity.

CONCLUSION

Even after controlling for underlying hospital and subject characteristics, women with prepregnancy class III obesity had significantly increased odds of postpartum readmission, and a trend toward increased odds of cesarean delivery, when delivering in institutions with less experience caring for women with obesity.