CHENNAI : The birth of a baby boy with the help of a frozen donor egg has given a boost to infertility treatment in India, giving childless women yet another option in assisted reproductive therapy. While it is common to freeze sperms and embryos, the consistency of success from frozen oocytes has been very limited, even though the procedure is more than two decades old. The first such baby was born in 1984 in Australia. So far, less than 100 babies have been born out of frozen oocytes.

The process involves cooling the oocytes to sub-zero temperatures using cryoprotectants (freezing media) and preserving them in liquid nitrogen jars at minus 196 degrees centigrade. When required , the eggs are thawed at room temperature using special thawing medium.

"We use different mediums and procedures. We have achieved a fair retrieval rate," said senior obstetrician- gynaecologist Dr Kamala Selvaraj , head of GG Hospital who on Wednesday assisted her daughter Dr Priya Selvaraj in helping a 29-year-old woman deliver the baby - claimed to be the first in India to be born out of frozen oocyte. The baby boy, weighing 2.5 kg was born after an elective caesarean in the 36th week of pregnancy by doctors at the GG Hospital in Chennai. The mother, who chose to be anonymous, was healthy and will be nursing the baby from Thursday.

With a history of frequent abortions resulting from chromosomal disorders, the woman approached GG Hospital . The doctors told her that she would require an egg replacement for a healthy pregnancy and decided to use the cryopreservation (freezing) method for a donor egg. "She came to us at a time when fertility procedures in the hospital were at their peak and it was impossible to find a donor. Fortunately, our hospital had started freezing eggs since 2005. We used an egg that was frozen in July 2006 as everything from the blood group to features of the patient matched with that of the donor," said Dr Priya Selvaraj, who performed the caesarean.

The procedure has been used with hesitation by several doctors, including experts abroad, as freezing and thawing could disturb the chromosomal structure in these cells and result in abnormalities in the embryos. "Oocyte is a specialized cell and extremely sensitive to the freezing and thawing process. The structural integrity of the cell has to be maintained throughout the cryopreservation process. But the advantages with this technique is that we can avoid multiple births that occur when frozen embryos are used as there is only one egg and one sperm used in the process," Dr Selvaraj said.