Trends, Characteristics, and Maternal Morbidity Associated With Unhoused Status in Pregnancy.

Importance: Unhoused status is a substantial problem in the US. Pregnancy characteristics and maternal outcomes of individuals experiencing homelessness are currently under active investigation to optimize health outcomes for this population. Objective: To assess the trends, characteristics, and maternal outcomes associated with unhoused status in pregnancy. Design, Setting, and Participants: This cross-sectional study analyzed data from the Healthcare Cost and Utilization Project National (Nationwide) Inpatient Sample. The study population included hospitalizations for vaginal and cesarean deliveries from January 1, 2016, to December 31, 2020. Unhoused status of these patients was identified from use of International Statistical Classification of Diseases, Tenth Revision, Clinical Modification code Z59.0. Statistical analysis was conducted from December 2022 to June 2023. Main Outcomes and Measures: Primary outcomes were (1) temporal trends; (2) patient and pregnancy characteristics associated with unhoused status, which were assessed with a multivariable logistic regression model; (3) delivery outcomes, including severe maternal morbidity (SMM) and mortality at delivery, which used the Centers for Disease Control and Prevention definition for SMM indicators and were assessed with a propensity score-adjusted model; and (4) choice of long-acting reversible contraception method and surgical sterilization at delivery. Results: A total of 18 076 440 hospital deliveries were included, of which 18 970 involved pregnant patients who were experiencing homelessness at the time of delivery, for a prevalence rate of 104.9 per 100 000 hospital deliveries. These patients had a median (IQR) age of 29 (25-33) years. The prevalence of unhoused patients increased by 72.1% over a 5-year period from 76.1 in 2016 to 131.0 in 2020 per 100 000 deliveries (P for trend < .001). This association remained independent in multivariable analysis. In addition, (1) substance use disorder (tobacco, illicit drugs, and alcohol use disorder), (2) mental health conditions (schizophrenia, bipolar, depressive, and anxiety disorders, including suicidal ideation and past suicide attempt), (3) infectious diseases (hepatitis, gonorrhea, syphilis, herpes, and COVID-19), (4) patient characteristics (Black and Native American race and ethnicity, younger and older age, low or unknown household income, obesity, pregestational hypertension, pregestational diabetes, and asthma), and (5) pregnancy characteristics (prior uterine scar, excess weight gain during pregnancy, and preeclampsia) were associated with unhoused status in pregnancy. Unhoused status was associated with extreme preterm delivery (<28-week gestation: 34.3 vs 10.8 per 1000 deliveries; adjusted odds ratio [AOR], 2.76 [95% CI, 2.55-2.99]); SMM at in-hospital delivery (any morbidity: 53.8 vs 17.7 per 1000 deliveries; AOR, 2.30 [95% CI, 2.15-2.45]); and in-hospital mortality (0.8 vs <0.1 per 1000 deliveries; AOR, 10.17 [95% CI, 6.10-16.94]), including case fatality risk after SMM (1.5% vs 0.3%; AOR, 4.46 [95% CI, 2.67-7.45]). Individual morbidity indicators associated with unhoused status included cardiac arrest (AOR, 12.43; 95% CI, 8.66-17.85), cardiac rhythm conversion (AOR, 6.62; 95% CI, 3.98-11.01), ventilation (AOR, 6.24; 95% CI, 5.03-7.74), and sepsis (AOR, 5.37; 95% CI, 4.53-6.36). Conclusions and Relevance: Results of this national cross-sectional study suggest that unhoused status in pregnancy gradually increased in the US during the 5-year study period and that pregnant patients with unhoused status were a high-risk pregnancy group.