Does quantity equal quality?-A morphokinetic assessment of embryos obtained from young women with decreased ovarian response to controlled ovarian stimulation

Purpose To assess oocyte quality in young patients with decreased ovarian response to controlled ovarian stimulation using time-lapse analysis. Methods A retrospective cohort study conducted at five medical centers between 2013 and 2017. The "decreased ovarian response" (DOR) group consisted of 241 women who underwent controlled ovarian stimulation with <= 5 retrieved oocytes and 519 cultured embryos. The "normal response" (NOR) group consisted of 667 women with >= 6 retrieved oocytes resulting in 3633 embryos. Data included annotation of morphokinetic events of embryos cultured in a time-lapse incubator from time of pronuclei appearance to time of starting blastocyst formation (tSB). Comparison was made between morphokinetic parameters of DOR and NOR patients with additional subgroup analysis according to the implantation status. Results Implantation and clinical pregnancy rates were significantly higher in the NOR group compared with the DOR group (44.5% vs. 31.6% and 51.5% vs. 37.7%, respectively; p < 0.05). Embryos from the DOR group reached the morphokinetic milestones later than embryos obtained from NOR patients. In the DOR group, implanted embryos reached starting blastocyst formation (tSB) faster than embryos which failed to be implanted, however, manifested a protracted course compared with implanted embryos from the NOR group. In a multivariate analysis-decreased ovarian response, nulliparity, number of transferred embryos, and t4, and were predictive for implantation. Conclusions The quantitative decrease in ovarian response is associated with reduced oocyte quality, reflected by a slower developmental rate and lower implantation and pregnancy rates.