Scientists have made a new discovery that might be of great help for women planning to have babies later in life.
For the first time, scientists have been able to identify the genetic factors that influence the age at which natural menopause occurs.
It is hoped that this can allow women in their late 30s and early 40s to pinpoint accurately how long they have left in which to conceive and when they should start trying for a baby.
Lisette Stolk, a researcher from Erasmus University Medical Center in the Netherlands, said at the annual conference of the European Society of Human Genetics that a greater understanding of the factors influencing age at menopause might also help to improve the clinical treatment of infertile women.
Stolk and colleagues analyzed genetic data from nine studies involving 10,339 menopausal women.
They found 20 single letter changes in the genetic code that were associated with having an early menopause.
The variants, known as single nucleotide polymorphisms (SNPs), were located at four different sites on chromosomes 19 and 20, two of the coiled packages of DNA that house the genes.
None of the variants had been identified before. What effect they have is unclear, but the scientists suspect they influence the ovaries or the brain.
"We found that the 20 SNPs were all related to a slightly earlier menopause and women who had one of them experienced menopause nearly a year earlier than others," said Stolk.
"We know that ten years before menopause women are much less fertile, and five years before many are infertile. In Western countries, where women tend to have children later in life and closer to menopause, age at menopause can be an important factor in whether or not a particular woman is able to become a mother," Stolk added.
Other effects of earlier menopause include an increased risk of the bone disease osteoporosis, the joint disease osteoarthritis and of heart disease, although it can also offer some protection against the risk of breast cancer.