Early-cleavage versus blastocyst stage embryo transfer: a prospective comparative study

To evaluate whether or not embryo transfer (ET) day has an effect on the rates of clinical pregnancy (CPR) and live birth (LBR) in in vitro fertilization-intracytoplasmic sperm injection (IVF-ICSI) treatment.

A total of 757 patients who underwent IVF-ICSI treatment between 2012 and 2017 were included. The participants were stratified into three groups according to ET day: group 1 (day 2 transfer, n=43); group 2 (day 3 transfer, n=633); and group 3 [day 5 (blastocyst) transfer, n=81]. Basal parameters and IVF-ICSI outcomes were compared between the groups.

Group 1 and 2 patients were older, had a higher body mass index, worse response rate, lower antral follicle count, lower peak estradiol levels, and less endometrial thickness, and required higher total gonadotropin dose than group 3. In addition, the number of oocytes and metaphase II oocytes, fertilization rate, and 2 pronucleus number were statistically different between the groups. The CPR (19.5% vs 36.9% vs 39.0%, respectively) and LBR (14.6% vs 30.4% vs 35.1%, respectively) were significantly lower in group 1 than in groups 2 and 3 (p<0.05). Grade 1 embryos were significantly more prevalent in groups 1 and 2 with clinical pregnancy positive [odds ratio (OR): 4.444; 95% confidence interval (CI): 0.876-22.536; p=0.001 and OR: 1.756; 95% CI: 1.234-2.500; p<0.001) and live birth (OR: 5.021; 95% CI: 0.787-31.768; p=0.001 and OR: 1.676; 95% CI: 1.154-2.433; p=0.007).

These data suggest that an earlier ET day has a negative effect on the CPR. Older primary infertile women should not postpone their desire to have a baby because they appear to be poorer responders.