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Did you know the menstrual cycle doesn’t end when the bleeding stops? While you’re counting down the days until you can live free of a tampon or Diva cup, the ovaries and uterus are prepping for more behind-the-scenes acrobatics.

There are four phases of the menstrual cycle:

  • menstrual phase
  • follicular phase
  • ovulation phase
  • luteal phase
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The length of each phase varies from person to person and can change over time. Let’s dive a bit deeper into what happens during each of these phases.

The menstrual cycle kicks off with everyone’s favorite part: the shedding of the uterine lining. When an egg from the last menstrual cycle hasn’t been fertilized (meaning no baby on board), then the menstrual phase begins.

During this period (literally!), estrogen and progesterone levels drop in the body.

Without the formation of a fetus, your uterus doesn’t need the thickened lining that develops throughout the month. So, like any smart, independent bodily organ, it kicks it to the curb by shedding it through the vagina. The result is your bloody period.

This process generally takes about 3 to 7 days, but varies from person to person. Using certain types of birth control can also impact period length and symptoms.

Here’s what you might experience during this phase:

  • cramps
  • sore or tender breasts
  • fatigue or tiredness
  • bloating
  • headaches
  • lower back pain
  • mood changes

Everyone’s different symptoms can vary widely. If you experience extreme period discomfort, talk to your doc.

The follicular phase overlaps with the menstrual phase and begins on the first day of your period.

This phase starts when the hypothalamus, a region of the brain responsible for hormone release, sends a signal to the pituitary gland to release follicle-stimulating hormone (FSH).

Next, the hormone “instructs” the ovaries to make small sacs (aka follicles). Inside each follicle lies a tiny, immature egg.

Only one egg of the pack will typically reach maturity. In rare cases, two eggs might mature. The leftover follicles are reabsorbed into the body.

The healthy follicle leads to an estrogen spike that thickens the lining of the uterus, creating a nutrient-rich environment for an embryo to grow. This phase typically lasts from 11 to 27 days, or an average of about 16 days.

Ovulation signals to your body that it’s baby-making time. This happens when hormonal changes tell the ovaries to release a mature egg.

Though it’s typically part of the menstrual cycle in peeps of reproductive age without fertility issues, it sometimes doesn’t happen at all. Other times, it happens twice in a cycle (which makes tracking this ish tricky).

Whether you want to get pregnant or are avoiding it, here are some ways to tell if you’re ovulating:

  • Your basal temp has risen slightly. Your basal temperature refers to your “normal” body temperature. Keeping tabs on it takes patience but can help pinpoint peak fertility. In order to boost accuracy, you’ll need to take your basal temp every morning at the same time before you get out of bed (with a basal temperature thermometer). This is part of the Fertility Awareness Method (FAM), which some use to plan or prevent pregnancy. Typically, you’re most fertile 2 to 3 days before your temp rises.
  • You have thicker discharge. If your discharge has taken on an egg-white texture with a white or yellow color, you’re probably pretty fertile. Low-fertility fluid is much less viscous and usually clear.
  • You’re cramping. Unfortunately, cramps aren’t always limited to the menstrual phase. Ovulation cramping, also called mittelschmerz, can last anywhere from minutes to days. It happens about 2 weeks before your period, or mid-cycle.
  • Your luteinizing hormone (LH) levels surge. During ovulation, your body starts producing more of the fertility hormone LH. Just like pregnancy tests, you can take an ovulation test to measure yours — they come in pee sticks, strips, and digital varieties. When the hormone peaks, you’re within 24 to 36 hours of ovulation range.


Sperm can survive in the body for up to 5 days, so you’re not necessarily protected from pregnancy if you have sex outside of the ovulation phase. To avoid pregnancy, always use birth control.

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Once the follicle releases an egg, it transforms into the corpus luteum (a cell mass that forms in an ovary and produces progesterone and estrogen). This hormone boost keeps the uterine lining thick and primed for a fertilized egg.

If you get pregnant, your body produces human chorionic gonadotropin (hCG), which pregnancy tests detect. If you don’t get pregnant, the corpus luteum reabsorbs into the body and hormones level out again.

This process is known as the luteal phase and it lasts about 11 to 17 days, with an average length of 14 days. Then, your period begins.

If you’re not pregnant, you might have some symptoms of premenstrual syndrome (PMS).

PMS symptoms include:

  • bloating
  • headache
  • mood changes
  • sexual appetite changes
  • sleep trouble
  • food cravings
  • weight gain

There are several factors that can impact a regular menstrual cycle, including:

  • Physical activity. Regular heavy exercise might cause missed periods.
  • The pill. While the pill typically makes periods more regular, it may take a few months. If you don’t take it consistently, it can also cause spotting.
  • Prescription drugs. Certain prescription drugs, like thyroid medication, antipsychotics, or steroids can impact your cycle.
  • Stress. Surges in stress can sometimes lead to irregular or missed periods.
  • Smoking. Smoking can impact the levels of progesterone, estrogen, and testosterone in the body, which could mess with your cycle.
  • Weight. Fluctuating weight might impact your menstrual cycle. Significant weight loss can lower estrogen levels, while weight gain can increase it.

While no two menstrual cycles are alike, significant abnormalities or changes may require medical attention.

Here are a few signs a trip to the doctor is in order:

  • Irregular or absent periods. Periods are considered irregular when they happen over 38 days apart or less than 24 days apart. Use a period app or a regular old calendar to ensure you’re on track.
  • Very painful cramps. Though it’s no fun, a little bit of cramping is normal. If your cramps feel debilitating or extreme, though, talk to your doctor. Severe cramps might signal the presence of endometriosis.
  • A persistent, heavy flow. Some people have light flows; others bleed a lot. In general, though, if you need to change a tampon within 2 hours, your menstrual cup every 2 to 4 hours, or have blood clots larger than a quarter, seek support. Heavy bleeding could signal PCOS.
  • Extreme fatigue. If you feel a little sore and sluggish during your period, you’re definitely not alone. If your cycle causes debilitating fatigue though, it might be a sign of anemia or another issue.
  • There are four menstrual cycle phases: menstrual, follicular, ovulation, and luteal.
  • Fertility tracking can serve as a useful way to help you get pregnant.
  • While conception happens during the ovulation phase, fertility tracking isn’t enough to prevent conception.
  • If your menstrual cycle is irregular, talk to your doctor — it could be the sign of an underlying issue.
  • If you feel extreme pain during your period, always consult a medical professional.