Children born from frozen embryos weigh more and do better than those born after fres...( This release is available in A HREF h...)

Barcelona, Spain: 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, Danish scientists reported to the 24th annual conference of the European Society of Human Reproduction and Embryology today (Tuesday 8 July). The mothers had longer pregnancies, and the children did not show an increased risk of congenital malformations, said Dr. Anja Pinborg, from the Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.

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.

Freezing embryos allows couples to have several cycles of IVF/ICSI from the same egg collection. The embryos are subsequently thawed and replaced three to five days after ovulation in exactly the same way as fresh embryos are used. The technique helps to reduce the number of times ovaries are stimulated and eggs collected.

The scientists found similar rates of multiple pregnancies in the FER groups (ICSI 11.7% and IVF 14.2%), but in the fresh embryo groups the rates were considerably higher (ICSI 24.8% and IVF 27.3%). Maternal age was significantly higher in the FER group. Pregnancy duration was significantly longer for these mothers, and birth weight was also higher about 200 grams in the FER group. The proportion of low
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