Here’s What Happens to Your Hormone Levels During Your Period

May 7, 2017 at 1:00 p.m. ET
Image: Getty Images

Being acquainted with what each time in your cycle means and the accompanying symptoms can help you better understand your period.

Let’s start by establishing how we count the days. Day 1 is the first full day of flow. The length of your cycle is counted from Day 1 of this cycle and until Day 1 of your next cycle.

Cycles vary widely — anything between 24 to 35 days is perfectly normal, but for simplicity sake, we often refer to a 28-day cycle. (This is especially applicable if you’re on birth control that works on a 28-day cycle.)

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Your cycle has two major phases, follicular and luteal, with a brief but crucial third phase, ovulation, in the middle. When it comes to your menstrual cycle, estrogen and progesterone are the primary hormone drivers. Fun fact: It’s what many forms of the birth control pill consist of. These hormones are secreted by the ovary, and are responsible for stimulating the lining of the uterus or womb, called the endometrium, to grow and prepare for a potential pregnancy.

The first phase of your cycle is called the follicular phase. This is because the main event during this phase is the creation of a follicle in the ovary. It is from this follicle that an egg is released, which is known as ovulation. This phase varies in length, but is usually between 12 and 16 days.

During your period in the first few days of your cycle, both estrogen and progesterone are low. Starting around Day 4 to 5, estrogen levels gradually begin to rise and what is called a dominant follicle forms. The dominant follicle prepares the egg for ovulation. Around cycle Day 10, estrogen production increases dramatically and progesterone slowly begins to rise. Estrogen surges around Day 12 to 13, meaning it shoots up, quadrupling levels, but then falls almost all the way back to pre-surge levels.

Twenty-four to 36 hours after estrogen surge, ovulation occurs. The dominant follicle releases an egg and becomes what is called the "corpus luteum." In a 28-day cycle, this is around Day 14.

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The last phase of your cycle, which is called the luteal phase referring to the corpus luteum, begins after ovulation. This part of your cycle is less variable in length and should consistently be 13 to 14 days. Both estrogen and progesterone rise sharply 1 or 2 days after ovulation. They peak about a week later around Day 20 to 22 and then if pregnancy does not occur, fall precipitously, resulting in low levels by Day 28. Now that your hormone levels are low, your next period starts, and it all begins again.

As you can see, there are some hormonal highs and lows throughout the month. Considering what is happening with your hormones may help to explain why some days you feel awesome and others not so much. For instance, according to Sarah Jio at Woman’s Day, during the first week of your cycle when estrogen levels are low, you may have less energy and a lower libido. So prepare for that. Plan for extra sleep if you’re tired or extra time with your partner if you notice your libido is low.

Menstrual migraines are a classic example. According to the Mayo Clinic, estrogen and progesterone may affect brain chemicals associated with headaches. Drops in estrogen, which occur both around the time of ovulation as well as premenstrually, can make headaches worse. Birth control pills can control headaches by keeping estrogen levels steady.

Although the exact causes are not known, the Office on Women’s Health states that an important cause of PMS is changing levels of hormones. Since PMS symptoms can begin anywhere from 1 to 2 weeks before your period starts, consider what is happening with estrogen and progesterone during that time. They are both rising dramatically and then falling precipitously. No wonder some women just don’t feel well during that hormonal roller-coaster ride.

“Every woman thinks that it’s the sudden drop in estrogen from not ovulating that causes the problems. But in reality, it’s the fluctuation of estrogen along with less progesterone that is behind many of the typical symptoms of perimenopause,” says Dr. Steven R. Goldstein, professor of obstetrics and gynecology at NYU Medical Center in New York City.

More: Irregular Periods Explained: 8 Big Reasons Your Period's Gone MIA

Understanding the elaborate hormonal changes that occur throughout the month and in what way they may affect how you feel — including your mood, energy and libido to name a few — can help you anticipate and prepare for the highs and lows. This way, you can ride the hormonal wave instead of being crushed by it.

By Katie Killoran

Originally published on HelloFlo.