Doubt cast on fertility technique

Dutch researchers have questioned the effectiveness of a technique that many fertility specialists believe improves the chances of pregnancy. Preimplantation genetic screening (PGS) harms the chances of motherhood for women older than 35, they claim. PGS involves removing a single cell from a three-day-old embryo and checking that a selection of chromosomes is normal. The technique is widely regarded as giving the best chance of success for older women undergoing fertility treatment, whose embryos are at greater risk of chromosomal abnormalities. But a study of more than 400 women aged 35 to 41 found that women receiving PGS had significantly lower pregnancy and live birth rates. Twelve weeks after the introduction of embryos, just 25% of those given PGS were pregnant, compared with 37% of controls. The team, led by are reported in the New England Journal of Medicine.... Whole on "nature":[ http://www.nature.com/news/2007/070702/full/070702-9.html]

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