BACKGROUND:
Preterm birth (PTB), i.e., birth <37 weeks’ gestation, is a leading cause of neonatal morbidity and mortality. Alberta has one of the highest rates of PTB in Canada. While midwifery-led care is associated with improved perinatal outcomes, the relationship between care model and PTB risk, and system-level factors shaping this relationship, remains understudied in Alberta.

OBJECTIVES:
To compare PTB risk between midwifery, family physician, and obstetrician-led care models in Alberta, and explore contextual factors that may contribute to risk differences.

METHODS:
This explanatory sequential mixed-methods study included: (1) a retrospective cohort analysis of 348,485 singleton births (2012–2022) using linked provincial administrative datasets; (2) 40 qualitative interviews with care providers (n=12), key informants (n=11), and people with lived experience (n=17). For the quantitative phase, risk ratios for PTB were calculated using adjusted log-binomial regression. For the qualitative phase, thematic analysis was used to explore how care models operate within the health system and influence clients’ experiences and birth outcomes.

RESULTS:
Quantitative findings showed significantly lower adjusted PTB risk among midwifery compared to family physician (RR 0.58, 95% CI 0.53–0.64) and obstetrician (RR 0.27, 95% CI 0.25–0.30) care recipients. Qualitative themes included: access and entry into care, time and workload, payment models, philosophies of care, and continuity. Midwifery care was consistently associated with emotionally safe, relationship-based care and earlier engagement, factors perceived to reduce stress and adverse outcomes. Systemic barriers in physician-led models included delayed entry and access, fragmented care and communication, and time-constrained visits.

CONCLUSIONS:
Both care model and health system structures influence PTB risk. The midwifery care model may offer protective relational and organizational features that merit broader health system planning and policy integration.

KEY MESSAGE:
Reducing PTB requires contextual system-level investment in midwifery and collaborative care structures prioritizing continuity, relational, equitable, and timely access to high-quality pregnancy care across all models. Poster session 2 (Group A)