Women who have a special genetic profile can conceive spontaneously after the age of 45 years, a scientist said at the 21st annual conference of the European Society of Human Reproduction and Embryology today (Tuesday 21 June 2005).
Dr. Neri Laufer, from the Hadassah University Hospital, Jerusalem, Israel, told the conference that his team's work to identify a specific gene expression profile linked to later fertility would help understanding of the ageing process, as well as enabling the development of better treatments for infertility in older patients.
Dr. Laufer and colleagues studied a large group of 250 women over 45 who conceived spontaneously. Women are generally not fertile after this age due to ageing of the ovaries, so the scientists thought that there might be some special factor that was allowing these women to conceive. "Mostly they had had a large number of children and also a low miscarriage rate", he said "and these two factors indicated to us that they had a natural ability to escape the ageing process of the ovaries. We decided to see if we could find any differences in gene expression between 8 such women and another 6 women of the same age group who had finished their families at the age of 30."
Using gene chip technology, the scientists found that blood samples from the 8 women had a unique pattern of gene expression that did not exist in the control group. The two main groups of genes expressed in these women were involved in apoptosis (cell death) and in DNA repair mechanisms. "These women appear to differ from the normal population due to a unique genetic predisposition that protects them from the DNA damage and cellular ageing that helps age the ovary", said Dr. Laufer. "What we do not yet know is whether this reproductive success is linked with potential longevity." The women were all Ashkenazi Jews but Dr. Laufer's team does not believe that the gene profile is unique to this group. "We already have preliminary results demonstrating similar results from another group", he said. The team intends to study women from different ethnic, and hence genetic, groups and study their genetic fingerprints against those of the first group.
Identifying women with these genetic fingerprints will enable doctors to know which women are still fertile at an advanced age and may determine the counselling they require, said Dr.Laufer. "However, the question of motherhood over the age of 45 is a delicate and complex one. It is very dependent on the religious and cultural background of the women in question. Our first study group came from an ultra-religious sector which encourages natural conception and discourages contraceptive use. These women would in any event continue to challenge their reproductive system until menopause. But for other groups the ethical implications may be different and counselling on all the aspects of late motherhood will play an important part in determining what is best for the individual woman."