Letrozole is an ovulation-promoting drug. When taken orally during menstruation, it helps the follicles to develop and grow to dominant follicles after 5 days of oral intake. If you have polycystic ovary syndrome, the cortex of your ovaries is thicker and you cannot ovulate on your own at this time. Similarly, if you want to have a multiple pregnancy, you can observe while taking oral letrozole, counting from the first day of your period, and go to the hospital on the sixteenth day for an ultrasound to rule out any rupture of the follicles. If the follicle does not rupture, it will form a luteal cyst at this time, which means that this ovulation is not effective and should be monitored for as long as possible.