Some women may be better able to get pregnant naturally after the age of 45 thanks to genes involved in aging.
Researchers studied a group of women who got pregnant without the aid of infertility treatments after age 45 and found that they had a unique genetic profile.
"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," says researcher Neri Laufer, of the Haddassah University Hospital in Jerusalem, in a news release.
He says it is not known whether these women's ability to protect the biological clock is linked with potential longevity.
Laufer presented his findings today at the 21st annual conference of the European Society of Human Reproduction and Embryology in Copenhagen, Denmark.
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Genes Play Role in Fertility
Researchers say female fertility decreases with age and conceiving a child naturally after age 45 is extremely rare. In addition, in vitro fertilization treatments are rarely successful in women over 45.
Women's fertility is thought to decline with age due to both decreased quantity and quality of eggs.
For the study, researchers identified eight Ashkenazi Jewish women over the age of 45 who had conceived naturally and compared their genetic profile with six other women in the same age group who stopped having children at age 30.
Gene analysis of blood samples from the women showed that the eight women who conceived after 45 had a unique pattern of gene expression that was not present in the other women.
The main groups of genes in these patterns were involved in cell death and DNA repair mechanisms.
Researchers say that screening women for these genetic patterns may help doctors know which women will still be fertile at an advanced age.
"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," says Laufer.
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SOURCES: 21st annual conference of the European Society of Human Reproduction and Embryology, Copenhagen, Denmark,June 19-22, 2005. News release, European Society of Human Reproduction.