Hormonal changes during menstrual cycle mainly include estradiol (E2), progesterone (P4), luteinizing hormone (LH), and follicular stimulating hormone (FSH).

The following figures depict changes of these hormones.During ovulation, serum estradiol (E2) level is about 300 pg/mL per ovum ovulation, progesterone (P4) level is about 2 pg/mL, luteinizing hormone (LH) is about 50 mIU/mL whereas follicular stimulating hormone (FSH) is about 25 mIU/mL. Physician will predict the timing of ovulation based on the changes of these hormonal levels, the sizes of mature follicles by ultrasound and patient’s clinical signs and symptoms.