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What Happens to Your Hormone Levels During the Menstrual Cycle?

Each cycle, the body works around the clock to prepare for a potential pregnancy. This means the brain and ovaries are constantly interacting to create hormone level changes over the course of each menstrual cycle. In this article, we'll see which hormones dominate in different cycle phases and how they influence your mental and physical fitness.

The menstrual cycle is a series of regular, natural changes in the female body. The length of the menstrual cycle is determined by the number of days from the first day of one period to the first day of the next. In other words, the first day of the menstrual cycle is the first day of your period.

The menstrual cycle has two main phases. The follicular phase, or proliferative phase, normally lasts the first 10–16 days of the cycle. The luteal, or secretory phase, comes right after ovulation and lasts for about 14 days, ending with menstruation if pregnancy didn’t occur. Generally, menstrual cycles that last from 21–35 days, with a  median duration of 28 days, are considered normal.

The female reproductive system is influenced by hormones that are regulated by the hypothalamus and the gonadotropin-releasing hormone (GnRH). GnRH causes the cells in the frontal part of the pituitary gland to produce two types of hormones.

The first is the follicle-stimulating hormone (FSH), and the other is luteinizing hormone (LH). These hormones travel all the way to the ovaries, where they influence estrogen and progesterone levels and aid the maturing of follicles inside the ovaries.

Some of the matured follicles will eventually release eggs, which will travel down the uterine tubes, where they can be fertilized before moving to the uterus. The complex hormone interaction that makes this possible is called the hypothalamic-pituitary-ovarian axis.

At the end of a cycle right before menstruation, estrogen and progesterone levels drop, causing an increase of FSH and GnRH levels.

All the hormones involved in the hypothalamic-pituitary-ovarian axis rise in one period of the menstrual cycle and drop in the other. All of these fluctuations affect ovulation and can cause symptoms like acne, negative mood, headache, weight gain, bloating, and appetite changes.

Now let's have a look at how hormone levels change during the cycle stages. 

During the follicular phase of the cycle, the increased levels of estrogen and the low levels of progesterone may improve the skin’s appearance. Improved mood is also associated with this phase. 

High levels of FSH in the early follicular phase stimulate folliculogenesis (growth and maturation of follicles). In the beginning of the cycle, many follicles grow equally until a dominant follicle emerges. 

Maturing follicles produce estrogen, which causes the luteinizing hormone to increase. High levels of estrogen and LH activate the complex biochemical interactions that lead to ovulation. 

Estrogen is one of the most impactful hormones in the female body. Estrogen is responsible for the stimulation of secondary female characteristics. It can also impact other aspects of female health, like mood stability, complexion, protecting bone health, and keeping cholesterol levels under control. 

Many people report a positive mood between days 6 and 14 of the cycle. For some, confidence slightly grows between days 6 and 13 of the cycle due to increased estrogen and testosterone levels. If you notice this is true for you, you might want to keep it in mind for scheduling appearances, meetings, or job interviews. 

Hormone levels on days 6–14 of the cycle can affect the skin’s scent, which can affect how fragrances and perfumes interact with your personal chemistry. 

Ovulation is the time when an egg is released from the dominant follicle and waits to be fertilized in a uterine tube. If your cycle is 28 days and regular and you're planning on getting pregnant, around 14 days before your next menstrual cycle begins is when you have the greatest likelihood of getting pregnant. However, sperm can survive in the uterus for about five days, and a released egg lives for about 24 hours, so conception is possible from sex that occurs at any point during this period of time, called the fertile window.

When the estrogen level peaks, it causes the luteinizing hormone level also to rise. This process kicks off ovulation and causes the egg to be released from the dominant follicle.

Ovulation is generally regular without any extra symptoms aside from changes in vaginal secretion — cervical mucus increases in quantity and becomes clear and stretchy, like egg whites, during this phase.

Different types of vaginal discharge occur throughout the cycle, so discharge that slightly changes color and consistency may be normal. During ovulation, there may be mild soreness on the side of the body where the ovary is releasing an egg. This is called mittelschmerz (German for "middle pain") and can last from a few minutes to 1–2 days. Mittelschmerz is completely normal, and it’s also normal not to experience it.

However, if you feel a sharp pain in your belly during the ovulation or there’s an excessive amount of discharge, it's possible that there are underlying health issues that need medical treatment.

After ovulation, LH and estrogen levels drop. The dominant follicle transforms into the corpus luteum, which is a sort of temporary organ that predominantly secretes progesterone to prepare the uterine lining for implantation of a fertilized egg.

This phase lasts for 14 days for most people. 

During the luteal phase, the body is preparing for implantation. Progesterone levels start to increase, which can start the onset of PMS, or premenstrual syndrome. Many people feel slightly off or unwell during the luteal phase.

The increased levels of progesterone typical of the luteal phase may cause irritability, negative mood, or skin issues. A spike in the hormone progesterone can cause constipation, because progesterone relaxes smooth muscles, including the bowel.

Common symptoms of the luteal phase include all of the known symptoms of PMS, such as:

For people who experience PMS, the luteal phase may bring discomfort and interfere with daily life. If you learn how to relieve PMS symptoms, you may gain an increased understanding of your body and be able to get through the luteal phase with minimal discomfort.

In the absence of a pregnancy, hormone levels start to decrease, and prostaglandin levels rise in the later part of the luteal phase. These changes cause the uterine muscles to contract, and the inner lining of the uterus (endometrium) is shed. This is menstruation, or your period.

The average period lasts from 4–6 days. But periods that last anywhere from 2–7 days are considered normal.

Since conception didn’t occur, progesterone and estrogen start to decrease. Some common menstrual symptoms include cramping, tenderness of the skin and breasts, sudden mood swings, tiredness, headaches and migraines, and lower back pain.

Many people feel uncomfortable, tired, and have a negative mood during menstruation. Fortunately, there are lots of medicines and foods that can help with this.

Some people who have intense cramps during their period often use pain-relieving medication. Others apply heating pads on the lower back and abdomen to ease the cramping pains.

Your period might last longer than average or be more intense. This shouldn't overly concern you, but it’s a good idea to talk to your health care provider about it to confirm that there aren’t any health issues affecting your periods. Dietary changes can help compensate for the loss of the nutrients from heavy bleeding.

Here's how to improve your life by getting to know your menstrual cycle.

  • Track your cycle using a calendar so you can anticipate symptoms.
  • Note personal observations on a calendar in order to adjust diet, skincare, and other activities accordingly.
  • The first days of your period are the best time to make changes to your diet. This is when progesterone and insulin levels are the lowest. Insulin levels create the feeling of hunger, so people feel less hungry when it’s low.
  • Changes in the blood glucose levels and insulin resistance due to fluctuations of progesterone affect your appetite. By being aware of how your cycle affects your insulin, you can track your appetite and cravings as a way to monitor your weight and health.

Here are the answers to the most common questions that the Flo users tend to ask about their monthly cycle. 

There are certain days of the month when you have the best chance of conception.

In theory, it's possible to get pregnant at any point in the menstrual cycle.

Because sperm can survive up to five days inside the uterus, it's impossible to say sex without birth control won’t lead to pregnancy, since a regular cycle may shift unpredictably.

However, the general rule is that the highest chances of getting pregnant are during the days leading up to and including ovulation — the fertile window. Tracking ovulation and the fertile window is especially important for people who are in the process of IVF or treating infertility.

You can have sex on any day of your menstrual cycle you want. However, during menstruation, the reproductive organs are more susceptible to infection.

  • If you find yourself consistently low on energy, schedule fewer activities during menstruation.
  • Schedule any trips or vacations around your cycle to make travel more enjoyable.
  • Pap smears are most accurate between days 9–20 of the cycle, so that’s the best time to schedule an appointment.
  • When estrogen levels are high (before ovulation and in the middle of the luteal phase), the body has its highest tolerance for pain, making this a good time to schedule appointments like waxing, getting a tattoo, or visiting the dentist. 

If you're experiencing severe symptoms due to hormonal changes, make sure to talk to a health care provider, who can run necessary tests. Because hormone imbalance can be caused by more serious conditions, it's important to keep your levels in check. 

Understanding how hormone levels change during the menstrual cycle can help you adjust your routines and optimize your life. A couple of minor lifestyle changes and calendar notes can really make a difference, so consider tracking your cycle to make the most of each month!




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