Adverse perinatal outcomes associated with homelessness and substance use in pregnancy.

Background: Women who are homeless during pregnancy may be exposed to poor nutrition, violence and substance use, yet the health status of their newborn infants has not been systematically evaluated. We undertook a study to provide preliminary estimates of the risk of adverse perinatal outcomes among Canadian women who are homeless or marginally housed during pregnancy, and the effect of concomitant substance use.

Methods: We conducted a retrospective cohort study at a single downtown hospital from October 2002 to December 2004, involving women who, during pregnancy, were homeless or underhoused (n = 80), substance users (n = 59) or neither (n = 3756). We noted neonatal measures such as birth weight and gestational age; the main study outcomes were preterm birth before 37 weeks' gestation, birth weight less than 2000 g and small for gestational age at birth.

Results: Homelessness or inadequate housing was associated with an odds ratio (adjusted for maternal age, gravidity and being a current smoker of tobacco) of 2.9 (95% confidence interval [CI] 1.4-6.1) for preterm delivery, 6.9 (95% CI 2.4- 20.0) for infant birth weight under 2000 g and 3.3 (95% CI 1.1- 10.3) for delivery of a newborn small for gestational age. Adjusted odds ratios for substance use during pregnancy were similar. In the combined presence of an underhoused or homeless state and maternal substance use, the adjusted risk estimates were 5.9 (95% CI 1.9-18.5), 16.6 (95% CI 3.5-79.3) and 5.6 (95% CI 1.1-28.7), respectively.

Interpretation: Homelessness and maternal substance use may reduce neonatal well-being through prematurity and low birth weight.