Comparison of gender and birth weight following day-three and blastocyst transfers.

Impact of blastocyst transfer on offspring sex ratio and the monozygotic twinning rate: a systematic review and meta-analysis

“…When we analyzed the M/F ratio after adding data from four unpublished studies (20)(21)(22)(23), blastocyst transfer resulted in an M/F ratio of 1.36 (1,071/ 790), which was significantly different from 1.05 (1,279/1,220) for the early cleavage-stage ET. The OR using fixed effect model was 1.29 (95% CI 1.13-1.47; I 2 ¼ 0%), which is almost equal to the OR including four published studies.…”

“…Five abstracts were excluded because of the absence of peer-review process and a full-length original article (15,(20)(21)(22)(23). Two reports on sex ratio imbalance after blastocyst transfer were excluded because there were no comparative data for blastocyst versus cleavage-stage ETs (5,24).…”

Blastocyst embryo transfer is associated with a sex-ratio imbalance in favor of male offspring

“…relative to the day of transfer, and considered these results attributable to their selection criteria based on cellular morphology, including observation of embryos with the healthiest ICM and trophectoderm formation (11). Two additional small studies retrospectively analyzed their own outcome data, and found only a nonsignificant trend toward more male offspring after human blastocyst transfers (2,12).…”

Blastocyst transfer and gender: IVF versus ICSI

“…Some earlier studies in human ART (assisted reproduction technology) have shown that blastocyst transfer may favour male offspring [17-21, 24, 29] while others did not come to the same conclusion [3,16,26,27,30]. However, reporting criteria are unclear as to selection between IVF and ICSI.…”