[Medically Assisted Reproduction in Natural Cycle: Outcome Evaluation of a Reproductive Medicine Department]

Medically assisted reproduction in natural cycle has been investigated, especially in women with poor response to conventional ovarian stimulation, with endometrial receptivity improvement, lower cost and possibility of successive cycles. The disadvantages are: lower profitability per treatment cycle and higher cancellation rate. The aim of this study was to determine the rate of clinical pregnancy in infertile women subjected to medically assisted reproduction in natural cycle.

Retrospective study of 149 medically assisted reproduction without ovarian stimulation of 50 infertile women, between January/2011 and October/2014.

The mean age of women undergoing medically assisted reproduction in natural cycle was 36.1 years. Approximately half (46.0%) of the cycles were performed in poor responders. On the day of ovulation trigger, the mean diameter of the follicle was 17.5 mm. Twenty-three cycles (15.4%) were canceled prior to ovulation trigger. In 8 cycles (5.3%), ovulation occurred between ovulation trigger and oocyte retrieval. In the majority of cycles (n = 118; 79.2%) oocyte retrieval was executed, a medically assisted reproduction technique was performed in 71 (47.6%), mostly intracytoplasmic injection. The overall fertilization rate was 77.5%. In 40 cycles (26.8%) there was embryo transfer. The implantation rate and the clinical pregnancy rate by embryo transfer was 35.0% and 25.0%, respectively. Most pregnancies occurred in poor responders, according to Bologna criteria.

Although the pregnancy rate per cycle started was 6.7%, the rate of clinical pregnancy per embryo transfer is quite satisfactory, being a group of women with unfavorable responses in previous treatments. The relatively high rates of cycle cancellation are mitigated by the greater simplicity and lower cost of these cycles.

The results obtained in this study demonstrate that Medically Assisted Reproduction in natural cycle may be an alternative treatment for ovarian stimulation in patients with poor prognosis, whose only alternative would be oocyte donation.