FSH (Follicle stimulating hormone) & LH (Luteinizing hormone) are female hormones which regulate your menstrual cycles. FSH rises in the first part of the cycle while LH rises after mid-cycle when ovulation takes place. These hormones are used to evaluate irregular periods, suspected failure of functioning of the sex organs, predict if you are ovulating and investigate infertility. Since their release is regulated by the pituitary gland in the brain, they also help to detect pituitary gland disorders.