Treatment-independent live birth after in-vitro fertilisation: a retrospective cohort study of 2,133 women.

STUDY QUESTION: What is the chance of a treatment-independent live birth following IVF (including ICSI) treatment?

SUMMARY ANSWER: Over 5 years of follow-up, the treatment-independent live birth rate was 17% in unsuccessfully treated women and 15% in those who had a live birth after IVF.

WHAT IS KNOWN ALREADY: A limited number of studies have investigated the chance of treatment-independent conception following completion of IVF, but most of them have been based on surveys with poor response rates and limited sample sizes.

STUDY DESIGN, SIZE, DURATION: This is a population-based, retrospective cohort study of 2133 women who received IVF treatment between 1998 and 2011 at a single regional IVF Unit and were followed for a minimum of 1 year and maximum of 15 years after their last IVF or ICSI treatment cycle.

PARTICIPANTS/MATERIALS, SETTING, METHODS: This study included all women, residing in the north-east of the UK, who attended the Aberdeen Fertility Clinic and received IVF treatment between 1998 and 2011. Clinical and diagnostic information of all women was linked with treatment and pregnancy outcome data. A total of 2133 women were divided into two groups: (i) those who achieved a live birth following successful IVF or ICSI treatment (n = 1060) and (ii) those in whom treatment was unsuccessful i.e. resulted in either no pregnancy or pregnancy loss (n = 1073). The two groups were followed from the date of the last embryo transfer until the first treatment-independent live birth or 31 December 2012, whichever came first. The primary outcome was the treatment-independent live birth rate at 1, 2.5, 5 and 10 years of follow-up. Cox regression was used to determine factors associated with treatment-independent live birth in each group.

MAIN RESULTS AND THE ROLE OF CHANCE: Within 5 years of follow-up, the treatment-independent live birth rate was 17% (95% CI, 15-19%) among women whose IVF or ICSI treatment was unsuccessful and 15% (95% CI, 12-17%) among women whose treatment resulted in live birth. In both groups, shorter duration of infertility, younger female age and IVF as compared to ICSI were associated with a higher chance of achieving treatment-independent live birth. Among unsuccessfully treated women, the chance of post-IVF live birth was reduced in those with tubal factor infertility. Three or more previous IVF or ICSI embryo transfers were associated with a lower chance of treatment-independent live birth among successfully treated women.

LIMITATIONS, REASONS FOR CAUTION: The study was conducted in a single fertility centre, which could compromise the generalizability of the findings. Moreover, data were unavailable on the women's use of contraception or active attempts to get pregnant, both of which could influence treatment-independent live birth rates.

WIDER IMPLICATIONS OF THE FINDINGS: This study provides a better understanding of the long-term prognosis for treatment-independent live birth after completion of IVF or ICSI treatment. The results will inform women of their chances of a treatment-independent live birth following failed or successful treatment and the factors that are associated with it.

STUDY FUNDING/COMPETING INTEREST(S): This work was funded by a Chief Scientist Office Postdoctoral Training Fellowship in Health Services Research and Health of the Public Research (Ref PDF/12/06). The views expressed here are those of the authors and not necessarily those of the Chief Scientist Office. The authors have no competing interests.

TRIAL REGISTRATION NUMBER: Not applicable.