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.