The main hormones in the menstrual cycle

The menstrual cycle is controlled by hormones. Hormones are chemical messengers transported through your bloodstream that tell your organs and cells to do different things.

There are four hormones involved in the menstrual cycle (actually, there are more than a dozen, but four lead the process). Each one has a different behavior, and its levels vary throughout the process, triggering different reactions in your body. The four phases of the cycle are created depending on the amount of each hormone present at any given time.

If you have a natural menstrual cycle (if you’re not taking or using any form of hormonal birth control, pregnant, or breastfeeding), then you’re somewhere on this hormonal continuum on any given day of your cycle.

In this post, I will briefly tell you which are the five key hormones in the menstrual cycle and their most important functions:

Your pituitary gland releases this hormone during the follicular phase. Its job is to stimulate the maturation of a few ovarian follicles (i.e., tiny sacs or “bags” that contain small immature eggs, called oocytes) in preparation to ovulate.

As the ovarian follicles grow, they will produce one type of estrogen called estradiol. Estradiol’s most important tasks are:

• Stimulate the growth of the endometrium in preparation for implantation.
• Stimulate the production of cervical mucus to facilitate sperm survival and transportation.
• Promote young and healthy skin, hair, and bones.
• Stimulate the left side of the brain for better logic, increased memory, and more focus.
• Boost serotonin.

Fun Fact: In addition to estradiol, your body produces other types of estrogen. According to Dr. Lara Briden, author of the book Period Repair Manual, you also get estrogen from fat tissue and intestinal bacteria.

This hormone is also secreted by the pituitary gland at the end of the follicular phase, and has two jobs. When it’s released, it causes the biggest (or more mature) ovarian follicle to break and release an egg into the uterine tubes, where it will wait for a sperm to potentially fertilise it. Additionally, LH transforms the empty follicle into a tiny gland called corpus luteum, which will be responsible for producing progesterone for the remainder of the cycle.

It’s produced in the ovaries after ovulation to help maintain and nourish a possible pregnancy (hence its name: pro-gestation). If there is no fertilisation, its levels drop, triggering your period. Progesterone’s main tasks are:

• Stop the growth of the endometrium, keep it in its place, and develop secreting glands to nurture a possible pregnancy.
• Stimulate a thick, dense, antimicrobial mucus barrier in the cervix to protect the reproductive organs and block sperm during the infertile days of your cycle.

This is the most important hormone when it comes to menstrual health. In addition to helping a possible pregnancy, it also:

• Reduces inflammation in the body.
• Helps build muscles.
• Promotes sleep.
• Prevents cardiovascular diseases.
• Calms the nervous system and enables you to cope with stress, among other things.

Women and people with periods also have testosterone but in small amounts. It’s produced in the ovaries and the adrenal glands during the ovulatory phase, and its main job is to stimulate your libido. It also increases motivation and helps you maintain muscle mass and strong bones.