Children born after a frozen, thawed embryo has been replaced in the womb have higher birth weight than those born where fresh embryos were used. The mothers had longer pregnancies, and the children did not show an increased risk of congenital malformations.
The scientists studied all the 1267 children born in Denmark between 1995 and 2006 after frozen embryo replacement (FER). The children were divided into three groups; those born after cryo-preserved IVF (878), those born after cryo-preserved ICSI (310), and 79 where the method of creation of the embryos was unknown. During the same period 17857 children were born after IVF/ICSI treatment using fresh embryos, and these children were used as controls. Data on the children’s outcomes, including congenital malformations, were obtained from Danish national registries.
 European Society for Human Reproduction and Embryology (2008, July 8). Children Born From Frozen Embryos Weigh More And Do Better Than Those Born After Fresh Transfer. ScienceDaily. Retrieved December 6, 2010, from http://www.sciencedaily.com /releases/2008/07/080708080707.htm