March 19, 2009

Woman Delivers Healthy Baby From Cryopreserved Egg

For the first time, a method of preserving the possibility of conceiving children for females who must undergo cancer treatment that results in infertility has successfully come to fruition, Reuters reported.  

A special procedure, developed by specialists at McGill University in Montreal, in which immature eggs ("oocytes") are removed from a woman's ovaries, then the oocytes are induced to mature in a lab dish, and finally they are preserved in a deep-freezer.  The oocytes remain in this frozen state until they are thawed for fertilization sometime in the future. 

This approach avoids the increase in estrogen that is essential for natural ovulation but which can be harmful for cancer patients, and does not demand postponement of cancer treatment.

Additionally, since eggs are being preserved and not embryos, donor sperm or male partner sperm does not have to be included at that time, Dr. Seang Lin Tan and associates explain in the medical journal Fertility and Sterility.  Young cancer patients find this particularly appealing.

They referenced the case of a woman, age 27, who had been experiencing complications in conceiving.  She did not have cancer, but was willing to attempt this new process. 

Eighteen immature oocytes, having undergone hormone treatment, were salvaged from the woman's ovaries by her doctors, followed by 48 hours of culturing in a maturation medium.  Then, 17 of the oocytes were cryopreserved in liquid nitrogen. 

Two months later, the eggs were thawed resulting in four surviving eggs.  Of these, three were fertilized by injection of a single sperm, and then relocated 2 days later into the womb of the patient.

The patient successfully delivered a healthy 7.5-pound baby girl, at 39 weeks gestation.  Dr. Tan's team indicated that the "examination of the newborn by a pediatrician found no evidence of congenital malformations, and the child has continued to develop normally."


Image Caption: Electron micrograph of a sperm fertilising a human egg. Yorgos Nikas/Wellcome Photo Library


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