The scientific and medical literature suggests, among other things, that pregnancy rates among women of "high" age may be increased by the use of PGD in addition to in vitro fertilization. A study by Dutch scientists published in the New England Journal of Medicine in 2007 doubts this. The study, which was carried out in several Dutch fertility clinics, examined the embryos of 206 women aged 35–41 using PGD for chromosomal damage. Only embryos without findings were transferred. Resulting in 29 births, the success rate of this group remained below that of a peer group that had not used PGD.