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The Fifth Vital Sign: Our Menstrual Cycle


Photo Credit: @juemwoman

You and your period. You’ve known each other since puberty, been through big emotions, awkward moments, and many sweatpants ‘n couch hangouts. But do you really know why she’s here? Or what she’s doing? We know that the basics of the menstrual cycle are often glossed over so we thought it would be worthwhile to check in with Perelel Medical Co-Founder, Dr. Banafsheh Bayati, MD, OB/GYN, FACOG, to revisit all of the period basics: what’s normal; what’s not; and why in the name of chocolate peanut butter cups PMS symptoms are so…real. Read on for the expert take.  

What is the purpose of a period?

    “Once menstruation starts, the lining of the womb develops with the rise of hormones at the start of each cycle. The lining is formed in order to prepare for pregnancy implantation. If fertilization does not occur and hormone levels fall, then the lining is shed in response to dropping progesterone. Thus, a period is the body releasing the tissue build up each month in preparation for possible pregnancy,” Dr. Bayati explains. 

    How long should it be? What's the range of normal?

      “Menstruation typically occurs every 21 to 35 days and can last for a few to seven days, typically. Menstruation typically starts around the age of 12 but can occur as early as age eight or as late as age 16 and the first several years following this start, cycles may be more irregular. In general, cycles tend to shorten and become more regular with age,” Dr. Bayati suggests.   

      What does it mean if your period is too long or too short?

        “If cycles are irregular then it is best to be evaluated. There are many causes for irregular cycles depending on the woman’s age, her personal and family history, as well as her diet and environment,” Dr. Bayati says. 

        What if your period is missing? Outside of pregnancy, what could that point towards?

          “If cycles suddenly stop occurring then pregnancy is first ruled out. Then a full evaluation is needed to address possible issues such as stress and illness. There are many other causes including medications, hormonal imbalances, weight changes, eating disorders and poor nutrition,” Dr. Bayati explains. 

          Why do PMS symptoms come on before your period?

            “PMS stands for premenstrual syndrome and is the name for a group of symptoms that a woman experiences in the luteal phase of menstruation which are typically 14 days prior to each menstruation start. These symptoms usually stop soon after the cycle starts.  


            PMS includes both physical and emotional symptoms that women can experience following ovulation as the hormonal levels of both estrogen and progesterone peak and begin to fall. These changing hormone levels may affect some women more than others,” Dr. Bayati explains. 

            At what point are PMS symptoms abnormal?

              “For most women PMS symptoms are mild but for some they can be severe and affect their life. Typically, this is called premenstrual dysphoric disorder or PMDD. PMDD can cause severe irritability and depression or anxiety starting one to two weeks prior to each cycle start. Symptoms usually resolve within one to three days after the start of the period. It is possible that PMDD is linked to serotonin levels in the brain as these levels change throughout the menstrual cycle and some women may be more sensitive to these changes,” Dr. Bayati says. 

              How much bleeding is in the normal range?

                “It is typical to bleed anywhere from five to 80 ml of menstrual fluid each cycle with averages at 30 to 60 ml per cycle. It’s important to note that if you are passing blood clots each cycle or have to restrict your activity for days each cycle, experience fatigue, or other symptoms of anemia, soak more than one tampon each hour for several hours each cycle or use double protection such as tampons and pads to prevent leaking, then you should see your doctor and assess your cycles for heavy bleeding,” Dr. Bayati suggests.  

                Are there any unexpected symptoms that may arise with your period?

                  “It is definitely common to experience digestive issues such as diarrhea, constipation, bloating and gas with menstruation. This is often due to a rise in hormones called prostaglandins, which help the womb contract and shed its lining as well as to contract and stop menstrual bleeding,” Dr. Bayati explains.  

                  Did we miss any of your period questions? Nothing’s off the table and no question is too basic or specific. Tell us on social or by dropping us an email. 

                  This article is for informational purposes only. It is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and we recommend that you always consult with your healthcare provider. To the extent that this article features the advice of physicians or medical practitioners, the views expressed are the views of the cited expert and do not necessarily represent the views of Perelel.

                  Written by Jessica Lopez. Jessica Lopez is a freelance writer, digital content creator, and new mother. She has covered all lifestyle topics ranging from bridal to beauty for publications including Brides Magazine, Byrdie, THE/THIRTY, and more. Walking wide-eyed into motherhood has inspired her to connect with other parents through her writing and shared experience. You can follow more of her journey @Jessica.H.Lopez.