OBJECTIVE: To explore whether women experiencing homelessness during pregnancy have higher risks of adverse pregnancy outcomes compared to housed women. DESIGN: Population-based retrospective cohort study using national electronic hospital records. SETTING: Maternity services across English NHS hospitals. POPULATION: Women giving birth at gestational age ≥ 24 weeks from January 1, 2013 to March 31, 2023. METHODS: Data were obtained from the English National Hospital Episode Statistics Admitted Patient Care database. Poisson regression models compared outcomes for women identified as homeless to housed women, adjusting for age, parity, ethnicity, year and pre-existing medical conditions. MAIN OUTCOME MEASURES: Severe maternal morbidity (SMM), preterm birth (< 37 and < 34 weeks), and low birth weight (< 2500 g). RESULTS: Among 3 349 601 women giving birth, 3301 (0.1%) experienced homelessness. Rates and adjusted risk ratios (aRR) comparing homeless to housed women were: SMM 2.5% versus 1.6% (aRR 1.28, 95% CI 1.02-1.59); preterm birth 11.8% versus 5.9% (aRR 1.88, 95% CI 1.69-2.08); and small for gestational age 9.0% versus 4.8% (aRR 1.56, 95% CI 1.38-1.76). Stratified by ethnicity, White homeless women had the highest risk for preterm birth and small for gestational age, while Asian homeless women showed the greatest risk for SMM, compared to White housed women. CONCLUSIONS: Homelessness recorded during pregnancy or at birth is associated with poorer maternal and infant outcomes. Interventions focusing on housing stability are key. Future research should explore housing dynamics beyond homelessness, including frequent moves and overcrowding, requiring detailed perinatal housing data.