In-vitro fertilization in completely natural cycles.

Our objective was to assess the efficacy of in-vitro fertilization (IVF) in natural ovarian cycles in couples with tubal and unexplained infertility. A prospective study design was used. A total of 39 fully investigated couples, who were patients at the Reproductive Medicine Unit, St Michael's Hospital, Bristol, UK, took part; they were diagnosed with either tubal disease (n = 26) or unexplained infertility (n = 13). Procedures involved daily capillary blood sampling, daily vaginal ultrasonography and vaginal oocyte recovery under sedation at mid-cycle. The main outcome measures were fertilization, implantation and pregnancy rates. Although more of the women with tubal disease were parous, there were no other significant differences between the two groups. The 39 couples with infertility of tubal or unexplained aetiology had 79 cycles of IVF in otherwise completely natural cycles. The overall fertilization rate was 80% and the implantation rate was 14.0%. A trend was observed for higher success rates in women with tubal disease. We conclude that natural cycle IVF and embryo transfer offers an acceptable chance of pregnancy and an opportunity for the in-depth investigation of follicular and ovarian function in couples with defined causes of infertility. The possibly lower success rate in women with unexplained infertility warrants further study of follicular function and endocrinology.