Evidence has accumulated in mammals suggesting a positive role for epidermal growth factor (EGF) as an inducer of oocyte maturation. The potential use of EGF as inducer of cytoplasmic and nuclear maturation was tested in women with > 10 oocytes retrieved in in-vitro fertilization (IVF), since we have previously observed that such oocytes are immature. Oocytes from 17 high responders were randomly allocated to one of the three treatment groups upon retrieval: control receiving no EGF (n = 93), 1.0 ng/ml EGF (n = 92) and 10.0 ng/ml EGF (n = 77) for 6 h before insemination. The rates of fertilization were respectively 54.6, 59.0, and 46.1%, suggesting that EGF is not effective at this maturational stage after this length of exposure. Embryo development was further analysed by the appearance of the embryos under the dissecting microscope and the number of blastomeres developed 48 h after insemination. No difference between groups was observed considering the number of blastomeres developed. However, embryos derived from oocytes treated with 10 ng/ml EGF displayed a worse appearance under the microscope. It is concluded that a 6 h incubation with EGF does not seem to affect cytoplasmic maturation in oocytes obtained after gonadotrophin treatment, as ascertained by the rate of fertilization following oocyte insemination.

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We did not find significant differences between the percentage of euploid blastocysts in each category. We also performed a logistic regression model for implantation, in which BMI, type of cycle and standard morphology were included. The model revealed an OR 3.20 (CI95% 1.57-6.50) (p¼0.001) comparing Xtend 1 vs 5 and an OR 2.52 (CI95% 1.23-5.19) (p¼0. 012).CONCLUSIONS: There is a direct correlation between Xtend categories, percentage of viable embryos, blastocyst rate, good morphology blastocyst rate and blastocysts available for biopsy. Regarding the implantation rate total, we observed significant differences between categories, even when we distinguished between fresh and frozen embryos.IMPACT STATEMENT: Retrospective nature of this study may be a reason for caution; nevertheless, it is the largest sample size reported with this test, based in blastocyst transfer with>90% of single-embryo-transfer. Additionally, a multivariable-analysis confirmed the magnitude of the results. It confirms that morphology and automatic time-lapse classifications can be used together to increase success rate in the laboratory.