STUDY QUESTION: What are the long-term chances of having a child for couples starting fertility treatments and how many conceive with ART, IUI and without treatment?

SUMMARY ANSWER: Total 5-year live birthrates were strongly influenced by female age and ranged from 80% in women under 35-26% in women ≥40 years, overall, 14% of couples conceived naturally and one-third of couples starting treatments with intrauterine insemination delivered from that treatment.

WHAT IS KNOWN ALREADY: Few studies report success rates in fertility treatments across a couple's complete fertility treatment history, across clinics, evaluating live births after insemination, ART and natural conceptions.

STUDY DESIGN, SIZE, DURATION: This register-based national cohort study from Denmark includes all women initiating fertility treatments in public and private clinics with homologous gametes in 2007-2010.

PARTICIPANTS/MATERIALS, SETTING, METHODS: Women were identified in the Danish ART Registry and were cross-linked with the Medical Birth Registry to identify live births. Subfertile couples were followed 2 years (N = 19 884), 3 years (N = 14 445) and 5 years (N = 5165), or until their first live birth. Cumulative live birthrates were estimated 2, 3 and 5 years from the first treatment cycle, in all women, including drop-outs. Birthrates were stratified by type of first treatment (ART/IUI), mode of conception (ART/IUI/natural conception) and female age.

MAIN RESULTS AND THE ROLE OF CHANCE: Within 5 years, in women aged <35 years (N = 3553), 35-39 years (N = 1156) and ≥40 years (N = 451), a total of 64%, 49% and 16% had a live birth due to treatment, respectively. Additionally, in women aged < 35 years, 35-39 years and ≥40 years, 16%, 11% and 10% delivered after natural conception, yielding total 5-year birthrates of 80%, 60% and 26%. In women starting treatments with IUI (N = 3028), 35% delivered after IUI within 5 years, 24% delivered after shift to ART treatments and 17% delivered after natural conception. Within 5 years from starting treatments with ART (N = 2137), 53% delivered after ART, 11% delivered after natural conception and 0.6% delivered after IUI.

LIMITATIONS, REASONS FOR CAUTION: Birthrates are most likely higher compared to countries without national coverage of treatments and results are influenced by laws and regulations. Information on duration of infertility prior to treatment was not available. Future prospective intervention studies should focus on the role of expectant management.

WIDER IMPLICATIONS OF THE FINDINGS: Our results can provide couples with a comprehensible age-stratified prognosis at start of treatment.

STUDY FUNDING/COMPETING INTEREST(S): This study was unconditionally funded by Ferring Pharmaceuticals and the Augustinus foundation. All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: S.S.M. received an unconditional grant from Ferring Pharmaceuticals; A.A.H. has received personal fees from Ferring Pharmaceuticals not related to this work; A.N.A. reports grants and personal fees from Ferring Pharmaceuticals, personal fees from Merck Serono, grants and personal fees from MSD, outside the submitted work; no financial relationships with any organizations that might have an interest in the submitted work in the previous 3 years; no other relationships or activities that could appear to have influenced the submitted work.

TRIAL REGISTRATION NUMBER: The study was approved by the Danish Data Protection Agency (J.nr. 2012-41-1330).