Menstrual Health: Understanding the Menstrual Cycle

Menstrual health is a key part of overall health. Throughout your cycle, hormone fluctuations reflect and affect many systems and functions in the body beyond just reproduction – including mood, sleep, digestion, heart health and bone density.

Learning about the menstrual cycle can help you notice patterns in your energy levels or mood and catch early signs of potential health problems. Even if you don’t get periods, understanding the menstrual cycle can help you support others who do.

What Is the Menstrual Cycle?

The menstrual cycle is a series of regular, natural changes in a woman’s hormones and reproductive system that prepare the body for a possible pregnancy. A normal menstrual cycle lasts anywhere from 21 to 35 days (average: 28 days) and starts on the first day of your period.

The menstrual cycle is divided into four phases:

• Menstrual phase

• Follicular phase

• Ovulation phase

• Luteal phase

Menstrual Phase

The menstrual phase starts on day one of your period and typically lasts 3-7 days.

The menstrual phase is the first stage of the menstrual cycle. It begins when the uterus lining, which was built up in preparation for a possible pregnancy, is no longer needed and is shed through the vagina – resulting in your period.

Levels of the hormones estrogen and progesterone are low at the beginning of the menstrual phase.

Follicular Phase

The follicular phase is the second phase of the menstrual cycle and typically lasts from day 1-14 of a standard 28-day cycle.

The follicular phase begins on the first day of your period, overlapping with the menstrual phase, and continues until ovulation.

During this phase, the ovaries begin to grow small sacs, called follicles, in response to rising levels of follicle-stimulating hormone. Each follicle contains an immature egg cell. As the dominant follicle matures, it makes increasing levels of estrogen. This surge in estrogen causes the lining of the uterus to thicken in preparation for possible pregnancy.

Rising levels of estrogen also trigger the release of luteinizing hormone - which starts the process of ovulation.

Ovulation

Ovulation is the third phase of the menstrual cycle and typically occurs around day 14 of a standard 28-day cycle, although timing can vary.

The egg that was growing in your ovary is now fully formed and ready to be released. This is called ovulation. The egg travels down the fallopian tube towards the uterus, where it can be fertilized by sperm.

Ovulation is the time during your cycle when pregnancy is most likely to happen, if sperm are present. While ovulation itself only lasts 12-24 hours, the full fertile window can span up to 5 days before ovulation, due to the lifespan of sperm.

If pregnancy doesn’t happen, the egg cell dies or dissolves.

Did you know? Pregnancy can happen as a result of sex 5 days before ovulation.

Luteal Phase

The luteal phase is the final phase of the menstrual cycle. occurring after ovulation and lasting until the start of your next period.

After the egg is released during ovulation, the follicle turns into a structure called the corpus luteum. This structure produces progesterone (and some estrogen) which keeps the lining of the uterus thick, preparing it for potential pregnancy.  

If you do get pregnant, your body will make the hormone human chorionic gonadotropin (hCG). hCG helps keep the lining of the uterus thick – it’s also the hormone pregnancy tests detect.

If pregnancy doesn’t happen, the corpus luteum will break down within 10-14 days. This leads to decreased levels of estrogen and progesterone, which triggers the start of your period and the beginning of a new cycle.

Mood Changes Throughout Your Cycle

Changes in hormone levels (mainly estrogen and progesterone) throughout the menstrual cycle can have a big impact on mood and overall energy levels. Many women feel their best physically, emotionally and mentally in the days leading up to ovulation.

Low mood is most common in the week or two before your period starts – and sometimes continues into the first few days of menstruation. You may also notice other symptoms of premenstrual syndrome (PMS) around this time, including:

• feeling depressed or irritable

• tiredness or trouble sleeping

• bloating or cramping

• breast tenderness

• headaches

• appetite changes or food cravings

• joint or muscle pain

• acne flare-ups

• constipation or diarrhea

The good news is that there are several evidence-based ways to help manage or reduce PMS symptoms, including lifestyle changes or medication, depending on their severity. Focus on eating nutritious foods, limiting caffeine and alcohol, exercising regularly, and practicing stress management.

When to Visit Your Healthcare Provider

If your period symptoms are interfering with your quality of life or if you notice unusual changes in your cycle, it’s always a good idea to talk to your healthcare provider. While some variation in your cycle is normal, certain symptoms or irregularities may signal an underlying issue.

See your healthcare provider if you experience any of the following red flags:

1. Missed periods, including if your period hasn’t started by age 15, you’ve missed 3 or more periods in a row, or your periods stop before age 45.

2. Irregular periods, such as if your cycle is consistently shorter than 21 days or longer than 35 days or if your cycle length varies widely from month to month.

3. Heavy bleeding, such as if your period lasts more than 7 days or if you soak through a pad or tampon every hour or couple of hours.

4. Severe pain, including extreme cramps that interfere with your daily life or if you have pain during sex or ovulation.

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Keeping track of your menstrual cycle – and the mood changes or physical symptoms that come with it – is a powerful first step toward understanding your body and overall health.

By monitoring patterns across your cycle, you can start to anticipate when you might feel your best and when challenges like PMS are likely to show up. Tracking your cycle also provides you with valuable information if you ever need to speak with your healthcare provider about your menstrual health.