Characteristics associated with planned home birth under midwifery care in Ontario, Canada: A population-based cohort study (2012-2018).

OBJECTIVES: To describe socio-demographic and clinical factors associated with planned home versus hospital birth. METHODS: A population-based cohort study of low-risk individuals in Ontario, Canada (2012-2018), under midwifery care at the onset of spontaneous labour. Modified Poisson regression was used to estimate adjusted relative risks and 95% confidence intervals. Population attributable fractions (PAFs) were calculated to describe the population-level proportion of planned home births associated with each factor. Analyses were stratified by parity. RESULTS: Among 85,259 eligible individuals, 20.2% of nulliparas and 29.2% of multiparas planned a home birth. Among nulliparous individuals, age ≥ 35 years and lack of health insurance coverage were among the strongest observed characteristics associated with planned home birth, whereas repeat midwifery care was the strongest observed characteristic associated with planned home birth among parous individuals. Gestational diabetes was among the strongest observed characteristics associated with planned hospital birth across parity groups, while prior cesarean birth was also strongly associated among parous individuals. Across parity groups, several categories representing missing or unknown information, including unknown race (reflecting no prenatal genetic screening) and missing or unknown geographic location, language and gestational diabetes data were also strongly associated with planned home birth. The largest PAFs were observed for repeat midwifery care (parous: 27.7%) and unknown race/ no prenatal genetic screening (nulliparous: 13.8%; parous: 13.9%). CONCLUSION: Planned home birth versus planned hospital birth was associated with distinct socio-demographic and clinical characteristics, as well as context-specific missing-data categories. These descriptive findings can inform future research.