Melbourne (PTI): If scientists are to be believed, women planning to delay motherhood could soon be able to take a simple blood test to determine the period of fertility they're left with.

In their study, a team at the Queensland University of Technology looked at the relationship of a reproductive hormone and menopause -- they found a wide variation in the age of menopause which for most women occurred between 40 and 60 years of age.

"But we know from studies of natural populations where timing of having children is not influenced by contraception, that natural fertility drops off ten years before menopause.

"This means that with the variation in menopausal age some women could become infertile as early as their 30s. It is then difficult to become pregnant without artificial intervention," the study's co-author Prof Malcolm Faddy said.

According to the researchers, the study used the fact that anti-Mullerian hormone (AMH) levels in blood reflected the number of small follicles present in a woman's ovaries.

"These follicles are responsible for the supply of eggs for ovulation, and depletion of the stock of follicles leads to menopause. The study measured AMH levels in blood samples from a group of healthy fertile women, using the data to determine a model of age-related change in AMH levels.

"We then used this model to predict age at menopause via a critical AMH threshold level. Prediction of menopause has been problematic since it is retrospectively defined as the cessation of menstruation for at least 12 consecutive months. But with prediction it becomes possible to forecast when natural fertility is in decline," Prof Faddy said.

He said that after validation of the model, this work could lead to a blood test which will assess the level of AMH being used to estimate the number of years of fertility left.

"Prediction for women younger than 30 remains problematic because AMH levels did not show much of a decline till after this age," the media quoted him as saying.