Substance use disorder and severe maternal morbidity: is there a differential impact?

Background: Substance use disorder (SUD) is a disease characterized by behavior patterns of substance use leading to dysfunction in cognition, mood, and quality of life. The prevalence of perinatal SUD in the United States continues to rise and has adverse effects on the maternal-infant dyad. Mirroring the rise in SUD is an increasing prevalence of severe maternal morbidity (SMM). However, this relationship needs further examination.

Objective(s): The primary objective of this study was to evaluate the association between perinatal SUD and SMM. We hypothesized that SUD would predict a significantly increased risk for SMM events, both as a composite and individually, in adjusted multivariable regression analyses.

Study design: We conducted a cross-sectional analysis of inpatient pregnancy hospitalizations from the Healthcare Cost and Utilization Project National Inpatient Sample from 2016 to 2020. ICD-10 codes were used to identify patients with an SUD and/or a SMM event. SUD was defined as a composite. Our primary outcome was rate of SMM as defined by the Centers for Disease Control and Prevention. Multivariable logistic regression analyses were performed to predict the likelihood of SMM among pregnancy hospitalizations with and without SUD as well as to predict the likelihood of SMM for each individual type of SUD in a subgroup of hospitalizations with SUD and SMM.

Results: Of the 3672,932 inpatient pregnancy hospitalizations included in the analyses, 6.27% (230,110/3,672,932) had SUD diagnosis and 2.10% (77,021/3,672,932) had an SMM diagnosis. The prevalence of SMM was significantly higher among patients with SUD (7357/230,110%-3.20%) vs without SUD (69,664/3442,822-2.02%, P<.0001). Patients with SUD were 1.5 times more likely to have a SMM event as compared to those without SUD (aOR 1.52; 95% CI 1.48-1.56). In subgroup analyses based on SUD type-the likelihood of SMM was strongest for stimulants (aOR 3.86; 95% CI 3.61-4.13) and sedatives (aOR 3.82; 95% CI 3.08-4.75). In subgroup analyses based on SMM event, SUD was a strong positive predictor for acute myocardial infarction (aOR 3.63; 95% CI 2.78-4.74) and aneurysm (aOR 6.28; 95% CI 2.77-14.21).

Conclusion(s): Pregnant patients with SUD carry significantly increased risk of experiencing an SMM event. These events occur more readily in patients with certain patterns of SUD use-most notably sedatives and stimulants. Patients with SUD were most likely to experience a cardiovascular-related SMM event, thus informing care.