A 13-year study of almost 9000 donor insemination treatments in 3333 consecutive patients at the London Women's Clinic, underlines the latest conclusions of the Human Fertilisation and Embryology Authority (HFEA).
The HFEA has reported that fertility treatment in same-sex female couples and single women is a dramatically increasing trend reflecting changing social attitudes and new family formations, also described by Professor Susan Golombok in her recent book We Are Family. Indeed, by the end of our study period – December 2016 – single, lesbian and female partners from heterosexual relationships comprised 45 percent, 43 percent and 12 percent respectively of our total patient population.
The HFEA data for 2018 showed that donor insemination resulted in an overall live birth rate per treatment cycle of 13 percent, with the lowest per-cycle rate found in single women. This, said the HFEA, was largely explained by patient age: single patients had an average age of 38 years, thus older than women in same-sex (33 years) and heterosexual relationships (34 years).
Our data similarly showed an age-related decline in success rates: from 12.5 percent per cycle in under 35s to 5.4 percent and below in the over 40s. Additionally, unlike the HFEA, we demonstrated the advantageous effects on outcome of cumulative treatments. We assessed our cumulative live birth rates (LBRs) in two ways: as a 'crude' rate over continuing cycles and as an 'expected' rate calculated to correct the analysis for the statistical effect of dropouts.
Again, crude cumulative LBRs declined with advancing patient age, from 29 percent in the under 35 group to 12 percent in the 40-42 years group. And similarly, while the calculation for expected cumulative LBRs revealed even higher rates, they still declined with age, from 66 percent in the under 35 group to 28 percent in the 40-42 year group. However, while the data just reported by the HFEA in their single-cycle results showed a lower LBR among single female patients, we found no difference in our cumulative success rates between the three treatment groups (same-sex and heterosexual couples and single women).
Over the 13 years of our study, overall dropout rates per cycle varied between 28 percent and 50 percent, and were even higher when plotted for age-specific cumulative dropout rate curves. The results thus show, first, that continued intrauterine insemination (IUI) treatments in these patient populations can yield results much higher than those reported by the HFEA for single cycles, and second, that dropout over time will have a significant negative effect on overall outcome: with each additional cycle number there are fewer and fewer patients who continue.
The other important result from our follow-up was that in both the crude and expected cumulative calculations, a plateau in success rates was reached after approximately six cycles in young women and three in older women. Thus, while persistence in treatment may well generate real benefits, additional benefits were not evident in more than six cycles. This supports the NICE advice of offering six IUI cycles as an initial course of treatment, but not a further six to those who have not conceived.
However, our real-life experience also challenges the HFEA recommendation that IUI is only a first-line option for women in same-sex relationships and not recommended for couples with unexplained infertility, mild endometriosis or mild male factor infertility. Our results were comparable over 13 years in all patient groups. The factors affecting outcome in our series were patient age, cumulative treatments and ovarian stimulation ahead of IUI, but not relationship status as reflected, albeit controversially, in the NICE guidance.