This hormone exists regularly in your menstrual cycle. In the first days of your cycle, after the conclusion of your period, FSH stimulates one of your ovaries to begin the final part of the development of the egg-bearing follicles.
Also, FSH stimulates this follicle to start producing oestrogen, which makes the endometrium (uterus´s inner layer) begin its rebuilding and, if you conceive, commands the shutting down of FSH secretion. This is why pregnant women do not ovulate.