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What Happens When You Get Your Period

Now that is a great question! We all know there is some bleeding for a few days, but did you know your reproductive organs are actually working all month long?

With four phases, a few key hormones, and an average 28 day cycle, the female reproductive organs are constantly working hard to keep the body ready for a potential pregnancy.

Menstrual Cycle

Menstrual Phase

During the menstrual phase you get your period. This phase begins when the mature egg from the previous cycle isn't fertilized (i.e. you aren't pregnant) leading to a drop in two key hormones, estrogen and progesterone. This leads to your uterine lining, which thickened to prepare for pregnancy, to shed through your vagina.

During your period you release a combination of blood, mucus, and tissue from your uterus. You may also experience cramps, bloating, headaches, tender breasts, and mood swings. Your period will last 3-7 days on average but varies from person to person.

Follicular Phase

The follicular phase begins on the first day of your period and lasts 11 to 27 days. This phase begins when your hypothalamus, an important part of your brain that helps with hormone production, tells your pituitary gland, another important hormone producer, to release the follicle stimulating hormone (FSH). This hormone triggers your ovaries to produce 5-20 follicles, small sacs that contain an immature egg.

Of those follicles, only one (sometimes two) will result in a mature egg while the rest are reabsorbed into the body. This mature egg causes your estrogen levels to rise which leads to a thickening of the uterine lining, which creates a nutrient-rich environment for a future embryo to grow.


The increased levels of estrogen in the follicular phase trigger your pituitary gland to release luteinizing hormone (LH), starting the ovulation process.

During ovulation your ovary releases the mature egg, which travels down the fallopian tube towards the uterus to be fertilized by sperm. This phase is the only phase in the cycle when you can become pregnant.

This phase happens in the middle of your menstrual cycle and only lasts about 24 hours. If the mature egg is not fertilized, it will die or dissolve.

Luteal Phase

Once the mature egg is released from the follicle, the follicle turns into the corpus luteum. This structure releases progesterone and some estrogen, keeping your uterine lining thick and prepared for a pregnancy.

If an egg is not fertilized, the corpus luteum will be reabsorbed, leading to a decrease in estrogen and progesterone, which kicks off your period.

During this phase, if a pregnancy does not occur, you may experience premenstrual syndrome (PMS) symptoms, which are very similar to period symptoms. This phase lasts between 11 to 17 days.

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