There is no way of predicting exactly when the menopause will occur
Scientists have identified genetic variants which affect the age when a woman reaches the menopause.
The researchers in the Netherlands believe the discovery might help with treatments for fertility problems.
Genetic data from nine studies involving 10,339 menopausal women were analysed by the team from Erasmus University in Rotterdam.
They found 20 changes in individuals' genetic codes that were associated with early menopause.
Such variants are known as single nucleotide polymorphisms (SNPs) and are located at four different sites on chromosomes 19 and 20.
The scientists suspect they influence the ovaries or the brain, although their precise effect is not yet known.
The findings were presented at the annual meeting of the European Society of Human Genetics in Vienna.
Researcher Lisette Stolk, from Erasmus University, said: "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.
"We know that 10 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."
The menopause usually occurs between the ages of 45 and 55.
The researchers now plan to analyse a larger sample of women using the same technique, known as a genome-wide association study.
Ms Stolk said she hoped the studies would allow them to understand better the function of the genetic variants involved in early menopause.
She added: "We might one day be able to screen women who have problems getting pregnant to see if they have one or more of these variants which might relate to their sub-fertility, and perhaps interfere with the relevant physiological pathways in order to delay their total infertility."