Purpose To determine if blastocyst transfer increases the ongoing and cumulative pregnancy rates, compared with day 3 embryo transfer, in women of all ages when at least 4 zygotes are obtained. Methods Prospective study including patients undergoing a first IVF/ICSI treatment and assigned to cleavage stage (n= 46) or blastocyst (n=58) embryo transfer. Supernumerary embryos were vitrified and patients failing to achieve an ongoing pregnancy after fresh embryo transfer would go through cryopreserved cycles. The main outcome measure was the ongoing pregnancy rate after the fresh IVF/ICSI transfer and the cumulative ongoing pregnancy rate. Results were also analyzed according to age (under 35 and 35 or older). Results A majority of patients (96.6 %) had a blastocyst transfer when at least 4 zygotes were obtained. The ongoing pregnancy rate was significantly higher in the day-5 group compared with the day-3 group (43.1 % vs. 24 %, p=0.041). The cumulative ongoing pregnancy rate was higher (but not significantly) with blastocyst than with cleavage stage embryos (56.8 % vs. 43.4 %, p=0.174). When analysed by age, patients 35 or older showed significantly higher ongoing pregnancy rate (48.4 % vs. 19.3 %, p=0.016) and cumulative ongoing pregnancy rate (58 % vs. 25.8 %, p=0.01) in the day-5 group compared to the day-3 group, while no such differences were observed in women under 35. Conclusions Blastocyst transfer can be suggested whenever there are at least 4 zygotes. While there are no differences in women under 35, the benefit of this option over cleavage stage transfer could be significant in women 35 or older.

This approach could be a simple, low-cost and effective way to decrease sperm DNA damage to normal values.

Purpose Studies have shown that embryo metabolism and cell cleavage after warming vitrified embryos is faster than after thawing frozen embryos. We study vitrified embryo transfer (VET) results depending on the developmental stage of warmed embryos and the duration of progesterone treatment before embryo transfer. Methods We designed a prospective study, patients were randomized in two groups, starting progesterone three (D+ 3) or four days (D+4) before embryo transfer. We recruited 88 patients with embryos vitrified on day 3. Results We didn't find statitistical differences in pregnancy rate when we transferred embryos in D + 3 vs D + 4 (38.2 % vs 40.5 % p ≥ 0.05). The day after warming, 54.6 % of embryos had developed to morula or early blastocyst, 32.4 % to cleavage stage and 13 % didn't cleave. Transfers were with morula/blastocysts stage embryos (52.1 %; n:37), cleavage stage embryos (18.3 %; n:13) or mixed (29.6 %; n:21). Implantation rate was significantly higher in morula/blastocyst stage than in cleavage stage or mixed transfers (44 %, 22 % and 16.3 %; p00.011). Pregnancy and implantation rates were significantly higher in morula/blastocyst transfers on D+4 than on D+3 (68.7 % and 64.7 % vs 33.3 %, and 33.3 %, p00.033 and p00.034). Conclusions Our findings suggest that a majority of embryos will develop to morula/blastocyst stage after warming. VET results with morula/blastocysts, and after four days of progesterone supplementation, are better than with cleavage stage embryos.