Researchers have refined an existing model that used serum levels of anti-Müllerian hormone to predict the age at which menopause starts. The model was tested in 1,015 women aged 20–50 years who were participating in the Tehran Lipid and Glucose Study. Serum levels of anti-Müllerian hormone were measured when the women entered the study, and their age at menopause was recorded over a 10-year follow-up. Over this time period, 277 women entered menopause. The model accurately predicted age at menopause in 92% of the women.