Extended culture of cleavage embryo to blastocyst embryo is among the good predictors of successful outcome in vitrified-thawed ICSI cycles

Background Previous studies showed that top-quality embryo transfer (ET), number of transferred embryos, endometrial preparation with natural cycles or mild stimulation, and female BMI independently affected the outcome in frozen-thawed ET. However, the effect of culturing thawed cleavage embryos to blastocyst stage on the outcome was not sufficiently elucidated. Our objective is to evaluate the role of this extended culturing as predictor of cycle outcome in vitrified-thawed ICSI cycles. Materials and methods One thousand forty-two consecutive cycles of vitrified-thawed ET done in a single IVF unit [Mansoura Integrated Fertility Centre (MIFC)] were reviewed during a period from 2014 to 2017. Endometrial preparation methods were natural, stimulation by antiestrogen and/or gonadotropins, or replacement using sequential estradiol (E2) and progesterone (P4). The primary outcome was the clinical pregnancy rate while the secondary outcome was the chemical and ongoing pregnancy rate. Results Overall clinical pregnancy rate (CPR) is 298/1042 is 28.5%, chemical pregnancy rate (326/1042) 31.3%, and ongoing pregnancy rate (167/615) 27.2%. Comparing clinically pregnant ( n = 298) and non-pregnant ( n = 744) showed, respectively, the following: age 28.76 ± 5.0, 28.85 ± 5.18 ( p = 0.8); BMI 31.06 ± 5.9, 32.45 ± 5.9 ( p = 0.002); infertility duration 4.17 ± 3.2, 4.6 ± 3.5 ( p = 0.038); endometrial thickness 10.82 ± 1.6, 10.13 ± 2.06 ( p = 0.0001); and no. of ET 3.35 ± 1.5, 3.12 ± 1.60 ( p = 0.035). The clinical pregnancy rate when vitrification was done on cleavage embryos was 198/502 (39.4%), and when vitrification done on blastocyst stage 100/ 536 (18.7%) ( P