A comparison of pregnancy outcomes between day 3 and day 5/6 embryo transfers: does day of embryo transfer really make a difference?

PURPOSE: To determine if day of embryo transfer (ET) affects gestational age (GA) and/or birth weight (BW) at a single university fertility center that primarily performs day 5/6 ET. METHODS: Retrospective cohort study of 2392 singleton live births resulting from IVF/ICSI at a single large university fertility center from 2003 to 2012. Patients were stratified by day 3 or day 5/6 ET. Outcome variables included patient age, gravidity, prior miscarriages, prior assisted reproduction technology cycles, number of embryos transferred, number of single ET, infertility diagnosis, neonatal sex, GA at birth, and BW. Subanalyses were performed on subgroups of preterm infants. A comparison was made between the study data and the Society of Assisted Reproductive Technologies (SART) published data. RESULTS: There was no difference in GA at birth (39 ± 2.1 weeks for day 3 ET, 39 ± 1.9 weeks for day 5/6 ET) or BW between ET groups (3308 ± 568 g for day 3 ET, 3268 ± 543 g for day 5/6 ET). There was also no difference in the number of preterm deliveries (8.5 % for day 3 ET vs. 10.8 % for day 5/6 ET). The day 5/6 ET study data had significantly fewer pre-term deliveries than the SART day 5/6 ET data. CONCLUSION: In contrast to published SART data, GA and BW were not influenced by day of ET. Data may be more uniform at a single institution. Day 5/6 ET continues to offer improved pregnancy rates without compromising birth outcomes.

A greater number of euploid blastocysts in a given cohort predicts excellent outcomes in single embryo transfer cycles.

PURPOSE: This multicentered retrospective study analyzed whether the quantity of euploid blastocysts in a given cohort after comprehensive chromosomal screening can be used to identify candidates for single embryo transfer. METHODS: Blastocysts from 437 patients underwent trophectoderm biopsy followed by array comparative genomic hybridization. Embryos were then selected for single or double embryo transfer. The number of euploid blastocysts produced and transferred for each patient was recorded, as was clinical pregnancy rate and multiple gestation rate. RESULTS: In patients with ≤ 3 euploid blastocysts, clinical pregnancy rate was higher in double, compared to single embryo transfers. However, in patients with ≥ 4 euploid blastocysts, clinical pregnancy rate was not reduced with single embryo transfer was performed, whereas the multiple gestation rate was greatly reduced. CONCLUSIONS: Size of the euploid embryo cohort is a marker for success in single embryo transfer cycles. Patients who produce at least four euploid blastocysts are outstanding candidates for single embryo transer.