Study leader MaryFran Sowers of the University of Michigan School of Public Health and colleagues examined the naturally occurring changes in three biomarkers over the reproductive life of more than 600 women : follicle-stimulating hormone , or FSH ; anti-Mullerian hormone , or AMH ; and inhibin B. The researchers found that the biomarker AMH declined to a very low or non-measurable level five years prior to the final menstrual period .