Boys more likely with early-stage embryo transfer

Friday, March 23, 2007

NEW YORK (Reuters Health) - Women undergoing assisted reproduction may be interested to learn that transfer of a "blastocyst-stage" embryo increases their odds of having a boy.

Blastocytes are the multiplying ball of cells that eventually implants in the uterus to become an embryo.

During in vitro fertilization, the most advanced embryos are typically selected for transfer. Findings from laboratory studies have indicated that these embryos are usually male. But whether this difference actually results in more boys than girls being born was unclear.

Dr. Alan B. Copperman, from the Reproductive Medicine Associates of New York, and colleagues assessed the sex-ratio of 1,284 offspring derived from either embryo transfer at day 3 or from blastocyst-stage transfer.

Male offspring dominated regardless of the stage of embryo development, they report in the journal Fertility and Sterility.

However, the difference was more pronounced with the use of blastocyst-stage embryos rather than with more mature embryos.

With blastocyst embryo transfer, 42.3 percent of offspring were female and 57.7 percent were male. With day 3 embryo transfer, 48.8 percent of offspring were female and 51.2 percent were male.

The authors believe that a revision of blastocyst selection criteria could help reduce the strong sex-ratio imbalance identified in this study.

SOURCE: Fertility and Sterility, March 2007.
http://www.nlm.nih.gov/medlineplus/news/fullstory_46977.html

Category: IVF