Associations between unstable housing, obstetric outcomes, and perinatal health care utilization

Background: While there is a growing interest in addressing social determinants of health in clinical settings, there are limited data on the relationship between unstable housing and both obstetric outcomes and health care utilization. Objective: The objective of the study was to investigate the relationship between unstable housing, obstetric outcomes, and health care utilization after birth. Study Design: This was a retrospective cohort study. Data were drawn from a database of liveborn neonates linked to their mothers’ hospital discharge records (2007–2012) maintained by the California Office of Statewide Health Planning and Development. The analytic sample included singleton pregnancies with both maternal and infant data available, restricted to births between the gestational age of 20 and 44 weeks, who presented at a hospital that documented at least 1 woman as having unstable housing using the International Classification of Diseases, ninth edition, codes (n = 2,898,035). Infants with chromosomal abnormalities and major birth defects were excluded. Women with unstable housing (lack of housing or inadequate housing) were identified using International Classification of Diseases, ninth edition, codes from clinical records. Outcomes of interest included preterm birth (<37 weeks’ gestational age), early term birth (37–38 weeks gestational age), preterm labor, preeclampsia, chorioamnionitis, small for gestational age, long birth hospitalization length of stay after delivery (vaginal birth, >2 days; cesarean delivery, >4 days), emergency department visit within 3 months and 1 year after delivery, and readmission within 3 months and 1 year after delivery. We used exact propensity score matching without replacement to select a reference population to compare with the sample of women with unstable housing using a one-to-one ratio, matching for maternal age, race/ethnicity, parity, prior preterm birth, body mass index, tobacco use during pregnancy, drug/alcohol abuse during pregnancy, hypertension, diabetes, mental health condition during pregnancy, adequacy of prenatal care, education, and type of hospital. Odds of an adverse obstetric outcome were estimated using logistic regression. Results: Of 2794 women with unstable housing identified, 83.0% (n = 2318) had an exact propensity score–matched control. Women with an unstable housing code had higher odds of preterm birth (odds ratio, 1.2, 95% confidence interval, 1.0–1.4, P < .05), preterm labor (odds ratio, 1.4, 95% confidence interval, 1.2–1.6, P < .001), long length of stay (odds ratio, 1.6, 95% confidence interval, 1.4–1.8, P < .001), emergency department visits within 3 months (odds ratio, 2.4, 95% confidence interval, 2.1–2.8, P < .001) and 1 year after birth (odds ratio, 2.7, 95% confidence interval, 2.4–3.0, P < .001), and readmission within 3 months (odds ratio, 2.7, 95% confidence interval, 2.2–3.4, P < .0014) and 1 year after birth (odds ratio, 2.6, 95% confidence interval, 2.2–3.0, P < .001). Conclusion: Unstable housing documentation is associated with adverse obstetric outcomes and high health care utilization. Housing and supplemental income for pregnant women should be explored as a potential intervention to prevent preterm birth and prevent increased health care utilization.