So how do these hormones work together to create your cycle? First your body produces the follicle stimulating hormone (FSH). This tells the ovaries that it is time to start maturing your eggs in preparation for ovulation.

The levels of hormones in your body change throughout your monthly cycle.

Many eggs begin the maturation process each cycle. The eggs residing in their follicles are ripening in preparation for release during ovulation. The follicle that the egg is living in produces estrogen. Estrogen is the major hormone in the follicular phase of your menstrual cycle.

When your body has reached its estrogen threshold, the luteinizing hormone (LH) is released. The amount of LH in your body jumps in quantity, which is known as the “LH surge.” This LH surge tells the most mature egg to release, in preparation for fertilization.

After the release of the egg (ovulation), the follicle where the egg came from becomes a corpus luteum (Latin for “yellow body”). The corpus luteum releases progesterone to help sustain the egg and build the uterine lining. The period of time between ovulation and menstruation is called the “luteal phase.”

If the egg is fertilized, eventually the placenta will take over hormonal production from the corpus luteum. If the egg is not fertilized, your progesterone levels will fall sharply. This drop in the progesterone levels signals your body that your period should begin, and the whole process starts again.