The number of oocytes as a predictor of pregnancy rates in the cycles of assisted reproductive technology

Background. Data on the effect of the number of received oocytes on the outcomes of assisted reproductive technology (ART) programs are contradictory. The frequency of obtaining a small number of cells ranges from 5.6 to 35.1 %. Identifying women who have chances of getting pregnant, despite this situation, is important for drawing up an adequate treatment plan.

Objective of this study is to assess the pregnancy rate depending on the number of retrieved oocytes in ART cycles with ovarian stimulation, which ended with the transfer of embryos, as well as determining the characteristics of patients with a reduced response, in whom the pregnancy occurred.

Design and methods. The study included 526 women who were treated for infertility in the department of ART of the Almazov National Medical Research Centre in 2017. Patients were divided into three groups depending on the number of oocytes retrieved: less than 5, from 5 to 9 and 10 or more. Group 1 (number of oocytes less than 5) included 126 women, group 2 (from 5 to 9) — 223 women and group 3 (number of oocytes 10 and more) — 177 patients. The average age of the patients was 33.37 years (from 22 to 48 years).

Results. The frequency of obtaining a positive blood test and clinical pregnancy rate were comparable in groups 2 and 3 (53.81 % and 49.72 %, respectively) and significantly lower in group 1 (41.27 %, p > 0.05). Clinical pregnancy in group 1 occurred in 34.13 % of cases, which was significantly different from the indicators of group 2 + 3, where the gestational egg visualized in 47.5 % of cases (p < 0.05). In a group of women with a small number of oocytes, the most important predictors of pregnancy were obtaining 2 or more oocytes, and anti-mullerian hormone (AMH) level above 1 ng / L.

Conclusion. The number of oocytes is an important predictor of pregnancy rate. The chances of becoming pregnant in women with a small number of oocytes depend on the level of AMH and the number of oocytes obtained.

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