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A Beginner's Guide to Understanding Your Menstrual Cycle

Do I have a normal menstrual cycle? And other important questions, answered.
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menstrual cycle, irregular menstrual cycle, period symptoms

When was your last period? How long is your menstrual cycle? Any abnormal discharge?

We’re asked these familiar questions at every annual gynecologic visit. But are we always sure how to answer? Since we don’t often go around comparing these parts of ourselves, we may not know what having a "normal" menstrual cycle actually means.


As most of us learn in middle school health class, the start of your period (and menstrual cycle) is the first day of bleeding. Your menstrual cycle is considered to be regular if the same amount of time passes consistently from the start of one period to the next (give or take three to five days). The number of days you experience bleeding does not determine whether your period is regular.

Many women worry that they are abnormal, infected, or somehow dirty because they see discharge on most days. If this is you, fear not! Discharge over the course of your cycle is normal due to regular hormonal changes that develop your eggs and prep your body in the case that you become pregnant. Unless the discharge has a foul odor or color, causes itching or burning, or is a change from what you’ve seen before, it’s probably harmless.


Even if we have a period every month, few of us know exactly what is going on inside our bodies to cause it. Until we do, it's hard to know what's normal or not. So get familiar with your body, and don't hesitate to ask your gynecologist any questions.

Everyone's menstrual cycle calendar is slightly different, but most of us follow the same menstrual cycle phases: on the first day of your period, your estrogen and progesterone hormone levels are relatively low. The hypothalamus in your brain monitors these levels and sends a message to inform another part of your brain, the pituitary gland, that they are low. The pituitary responds by releasing two other hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Both serve as messengers that head toward your ovaries.

Once the FSH reaches your ovaries, it stimulates the cells surrounding each of your immature eggs to produce estrogen. As your estrogen level rises, the lining of your uterus starts to build up again. Your cervix produces more mucus and you’ll experience an increase in vaginal discharge, which is usually a thick white or pale yellow paste, for a few days, followed by a thinner watery fluid. Finally, at the peak of estrogen levels, you’ll see a clear, slippery fluid. This is the most fertile time of your menstrual cycle.

At this point, your pituitary gland sends out a surge of LH to your ovaries, which release chemicals called prostaglandins. The cells surrounding each egg rupture, and the egg inside is released—this is ovulation. Some women feel cramping or even see a bit of spotting in the middle of their menstrual cycle when this occurs.

The released egg now travels down your fallopian tube toward your uterus. Meanwhile, the leftover cells take on a new function, producing progesterone instead of estrogen. You may see changes in your discharge again at this point. The sudden drop in estrogen and rise in progesterone thickens the cervical secretions, causing the slippery discharge to end abruptly. The progesterone thickens and stabilizes the uterine lining. If the traveling egg is fertilized, your body will continue producing progesterone to maintain a thick lining for the pregnancy. If fertilization does not occur, the lining begins to degenerate.

Progersterone and estrogen levels fall, triggering another release of cramp-inducing prostaglandins, as well as other familiar premenstrual symptoms (PMS) such as breast tenderness, bloating, headaches, and irritability. The uterine lining is shed—the start of another period. Your brain now notices the levels of estrogen and progesterone are low, and the whole menstrual cycle begins again.


Well the reality is that many women don't have perfectly normal menstrual cycles. This doesn't necessarily mean that something is wrong! But as you may have guessed from the above explanation of how your cycle works, there are a lot of places where only a small deviation will result in irregular symptoms.

So yes, that means that if you have many days of spotting before true menstrual bleeding starts or if your discharge has a foul odor or color, causes itching or burning, or is a change from what you've seen before, you should mention it to your gynecologist. And if the only solution they offer is hormonal birth control, ask if there's another option. Birth control tends to treat the symptoms without addressing the root problem.

Ultimately your best bet is to communicate with your doctor. Keep a log of your cycles and symptoms, including bleeding, discharge, and even changes in stress or diet, for a few months before your appointment. That information will help guide your doctor to order appropriate diagnostic tests, which may include blood work or ultrasound imaging. And let them know ahead of time if you prefer to avoid birth control so they can consider that when giving recommendations. There are effective hormonal options that do not involve birth control or "shutting off" the menstrual cycle, and a good provider should be willing to work with you to find a treatment that works for both your medical condition and your preferences.

Art by Cate Parr