FROZEN embryos do better than fresh. That鈥檚 the surprising conclusion of a study of children conceived by IVF which set out to address concerns that freezing might harm embryos.
Anja Pinborg of Copenhagen University Hospital in Denmark studied more than 1200 children born in the country between 1995 and 2006 as a result of IVF using frozen embryos and compared them with almost 18,000 children born after conventional IVF using fresh embryos.
The frozen embryos produced babies of roughly normal birth weight, while those from conventional IVF were on average about 200 grams lighter, Pinborg told the European Society of Human Reproduction and Embryology in Barcelona, Spain, on 8 July.
Advertisement
Freezing an embryo shortly after fertilisation is unlikely to improve its viability, though. An alternative explanation, Pinborg argues, is that embryos able to survive the freezing and thawing process are likely to be healthier. 鈥淭here鈥檚 selection,鈥� she suggests.
What鈥檚 more, women who have eggs frozen for later use tend to be younger and in better physical shape. And unlike women given conventional IVF, they will not be trying to establish a pregnancy immediately after being given hormone treatment to harvest their eggs 鈥� which it is thought could impair the process of implantation.
Pinborg鈥檚 team also found that babies from frozen embryos were no more likely to suffer birth defects or neurological problems than conventional IVF babies.
