Postpartum Readmission Risk: A Comparison between Stillbirths and Live Births.

BACKGROUND: Stillbirth occurs more commonly in pregnant people with comorbid conditions and obstetric complications. Stillbirth also independently increases maternal morbidity and imparts psychosocial hazard compared with live birth. These distinct needs and burden may increase the risk for postpartum readmission after stillbirth.

OBJECTIVE: To examine the risk of maternal postpartum readmission after stillbirth, in comparison with live birth, and to identify indications for readmission and associated risk factors.

STUDY DESIGN: A retrospective cohort of patients with singleton stillbirths or live births delivered at ≥20 weeks gestation was identified from the 2019 Nationwide Readmissions Database. The primary outcome was all-cause readmission within 6 weeks of discharge from childbirth hospitalization. The association between stillbirth (versus live birth) and risk of readmission was assessed using multivariable regression models adjusting for maternal age, sociodemographic characteristics, maternal and obstetric conditions, and delivery characteristics. Within the stillbirth group, risk factors for readmission were further examined using multivariable regression. The secondary outcomes included principal indication for readmission (categorized based on principal diagnosis code of the readmission hospitalization) and timing of readmission (number of weeks after childbirth hospitalization). Differences in these secondary outcomes were compared between the stillbirth and live birth groups using Chi-square tests. All analyses accounted for the complex sample design to generate nationally representative estimates.

RESULTS: Postpartum readmission occurred in 2.7% of 16,636 patients with stillbirths, compared with 1.6% among 2,870,677 patients with live births (unadjusted risk ratio [RR]=1.65, 95% confidence interval [CI]: 1.47-1.86). The higher risk of readmission after stillbirth (versus live birth) persisted after adjusting for maternal, obstetric, and delivery characteristics (adjusted RR 1.27, 95% CI: 1.11-1.46). The distribution of principal indication for readmission differed after stillbirth versus live birth: hypertension (30.2% vs. 39.5%, unadjusted RR=0.76, 95% CI: 0.63-0.93), mental health/substance use disorders (6.8% vs. 3.6%, unadjusted RR=1.90, 95% CI: 1.15-3.16), and venous thromboembolism (5.8% vs. 2.0%, unadjusted RR=2.87, 95% CI: 1.60-5.17). Among patients with stillbirths, 56.0% of readmissions occurred within 1 week, 71.8% within 2 weeks, and 88.1% within 4 weeks; the timing of readmission did not differ significantly after stillbirth versus live birth. Pregestational diabetes (adjusted RR=1.87, 95% CI: 1.20-2.93), gestational diabetes (adjusted RR=1.67, 95% CI: 1.03-2.71), hypertensive disorders of pregnancy (adjusted RR=1.80, 95% CI: 1.31-2.47), obesity (adjusted RR=1.46, 95% CI: 1.01-2.12), and primary cesarean (adjusted RR=1.74, 95% CI: 1.17-2.58) were associated with a higher risk of readmission after stillbirth, whereas higher household income was associated with a lower risk of readmission (e.g., adjusted RR for ≥$82,000 versus $1-47,999 = 0.48, 95% CI: 0.30-0.77).

CONCLUSION: Compared with live births, risk of postpartum readmission was higher after stillbirths even after adjustment for differences in patients' demographic and clinical characteristics, and readmission after stillbirths was more likely due to mental health/substance use disorders and venous thromboembolism.