Socioeconomic disparities in achieving a live birth after initiating ART treatment: a national register-based study among women in Denmark.

study questionHow are educational level, labour market attachment, and income associated with achieving a live birth following ART treatment initiation among women in Denmark? SUMMARY ANSWER: Higher educational level, labour market attachment, and higher income were strongly associated with achieving a live birth after initiating ART treatment among women in Denmark. WHAT IS KNOWN ALREADY: During the study period 1994-2017, three 'fresh' IVF or ICSI treatments with hormonal stimulation were offered free of charge in public healthcare in Denmark, while additional ART treatments were self-financed in the private healthcare sector. Earlier research indicates that higher socioeconomic position (SEP) increases the probability of initiating ART treatment; however, knowledge about SEP and its relation to outcomes after ART treatment is limited. STUDY DESIGN SIZE DURATION: This is a national, register-based cohort study based on the Danish National ART-Couple (DANAC II) Cohort. Women initiating ART treatment during 1994-2017 were identified in the Danish IVF register and individually linked with data from sociodemographic registries and the Medical Birth Registry using the Danish Personal Identification number. The study population comprised 68 738 women who initiated ART. The women were followed until achieving a live birth, death, migration, or end of study (31/12/2017). The median follow-up time was between 1.3 and 1.9 years. PARTICIPANTS/MATERIALS SETTINGS

methodsWomen included in the analyses were aged 18-45 years. Overall associations between achieving a live birth after initiating ART treatment and educational level, labour market attachment, and income were examined and further stratified by nulliparity at baseline and age group. Hazard ratios (HRs) with confidence intervals (CIs) were estimated by Cox proportional hazards regression, and with adjustment for potential confounders including age and ethnicity. Live births refer to both treatment and non-treatment-related births. MAIN RESULTS AND THE ROLE OF CHANCE: Adjusted results showed that educational level, labour market attachment, and income significantly determined the probability of achieving a live birth after initiating ART treatment. HRs of achieving a live birth after initiating ART treatment increased stepwise with higher education and income level, respectively. Compared with primary school education, the highest HR was found among women with a research education (adjusted HR (aHR) = 3.02 [95% CI, 2.71; 3.35]). Unemployed women had the lowest HR of achieving a live birth after initiating ART treatment (aHR = 0.67 [95% CI, 0.64; 0.69]) compared to employed women. Women at the highest income level had two times higher HR (aHR = 2.00 [1.94; 2.06] of achieving a live birth after initiating ART compared to women at the lowest income level. Analyses of different age groups showed that higher SEP was associated with a live birth after ART treatment in all ages. The same consistency was found for both childless women and women who had a child or children prior to ART treatment. Analyses showed that women with higher SEP were more likely to continue ART treatment after unsuccessful attempts, which could explain the observed social inequality in achieving a live birth after ART treatment. LIMITATIONS REASONS FOR CAUTION: The Danish IVF register did not register non-ART treatments (intrauterine inseminations) before 2007; thus, these treatments were not included. Whether the severity of infertility differs among SEP groups is unclear. Also, geographical distance to fertility clinics could have provided additional perspectives. WIDER IMPLICATIONS OF THE

findingsFree access to fertility treatment in public healthcare should ideally provide equal access. Patients encounter barriers during treatment, and as shown, treatment success differs based on socioeconomic background. Difficulties encountered during treatment that challenge certain patients more than others based on their socioeconomic background need to be considered further. STUDY FUNDING/COMPETING INTERESTS: No specific funding was achieved for this project. The authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER: N/A.