加拿大出生与移民不孕女性的生殖结局：安大略省基于人群的队列研究

STUDY QUESTION: Do reproductive outcomes, including live birth rates, differ between Canadian-born women and immigrant women with infertility in Ontario, Canada?

SUMMARY ANSWER: Immigrant women with infertility, particularly refugees, had lower probabilities of live birth within 2 years of diagnosis compared with Canadian-born counterparts.

WHAT IS KNOWN ALREADY: Immigrant populations experience barriers to fertility care, yet population-level data on reproductive outcomes among immigrant women diagnosed with infertility are limited.

STUDY DESIGN, SIZE, DURATION: This population-based retrospective cohort study used linked administrative and registry data from ICES (formerly the Institute for Clinical Evaluative Sciences) Ontario between 2010 and 2019, with follow-up through 2021. The cohort comprised 254 463 women aged 18-55 years with a new physician-diagnosed infertility visit (OHIP 628), including 177 289 Canadian-born (69.7%) women, 66 131 non-refugee immigrants (26.0%), and 11 043 refugee immigrants (4.3%).

PARTICIPANTS/MATERIALS, SETTING, METHODS: Immigration status (Canadian-born, non-refugee immigrant, refugee immigrant) was derived from Immigration, Refugees and Citizenship Canada (IRCC-PR) data. The primary outcome was live birth within 2 years of infertility diagnosis. Secondary outcomes included time-to-pregnancy and birth by assisted conception. Relative risks were estimated using log-binomial regression and fecundability odds ratios (FORs) using discrete-time Cox models, adjusting for age, parity, income quintile, rurality, chronic conditions, and index year. Analyses followed the STROBE reporting guidelines.

MAIN RESULTS AND THE ROLE OF CHANCE: Among 177 289 Canadian-born, 66 131 non-refugee immigrant, and 11 043 refugee immigrant women, live birth within 2 years occurred in 68 394 (38.5%) Canadian-born women, 22 363 (33.8%) non-refugees, and 3525 (31.9%) refugees, with aRRs of 0.96 (95% CI 0.94-0.97) and 0.90 (95% CI 0.87-0.94), respectively, compared to the Canadian-born cohort. The median time-to-pregnancy was 10 months (IQR 4-23) for Canadian-born women and 11 months (IQR 4-24) for immigrants, with reduced fecundability among both non-refugee (aFOR 0.97, 95% CI 0.96-0.99) and refugee immigrants (aFOR 0.89, 95% CI 0.86-0.91). Among those who achieved pregnancy, births by assisted conception occurred in 21 449 (24.5%) Canadian-born women, 5174 (17.6%) non-refugees, and 666 (14.4%) refugees, with adjusted RRs of 0.73 (95% CI 0.70-0.75) and 0.64 (95% CI 0.60-0.69), respectively, compared to the Canadian-born cohort.

LIMITATIONS, REASONS FOR CAUTION: Administrative data capture physician-diagnosed infertility, which may under-represent immigrants who are less likely to receive a diagnosis, leading to potential selection bias and underestimation of disparities. Residual confounding and incomplete ascertainment of conception type or social determinants remain possible.

WIDER IMPLICATIONS OF THE FINDINGS: Despite universal health coverage and a publicly funded IVF program, inequities in fertility outcomes persist for immigrants, especially refugees. These findings underscore the need for equity-focused fertility policy that addresses cultural acceptability, diagnostic access, and integration of mental-health supports in reproductive care.

FUNDING: This study was supported by the Canadian Institutes of Health Research (CIHR) Project Grant Impact of Infertility and its Treatment on Women's Mental Health (FRN 165840). The research was conducted at ICES, which is funded by an annual grant from the Ontario Ministry of Health and the Ministry of Long-Term Care.

DISCLOSURES: None of the authors report conflicts of interest relevant to this study.

TRIAL REGISTRATION NUMBER: Not applicable.