Menstrual Cycles 101 – Part 3: Where is my period?

Now that you’ve hopefully read the basics of Menstrual Cycles, part 1, and common issues surrounding periods in part 2, I want to take the time to discuss what might be happening if you have no period at all, also known as Amenorrhea.

As always, let’s start with a quick recap from the basics article on what a “normal” period is considered to be. 

According to The American College of Obstetricians and Gynecologists, most ovulatory menstrual cycles last 21 to 35 days. The duration of actual blood flow generally lasts 5 days, with the heavier flow hitting in the first 3 days. This can vary by a few days and become longer or shorter – especially as women approach menopause. The amount of bleeding over the course of your period should be less than one third of a cup. If you use pads or tampons, it may be hard to quantify this, but typically, you should not have to change your pad more frequently than every 2-4 hours.  

The most common causes of absent periods are related to hormonal changes that can be caused by the following:

  • Athletes
  • Low body weight
  • Polycystic Ovarian Syndrome (PCOS)
  • Thyroid
  • Pregnancy
  • Medication

Now let’s take a deeper look into these common causes of Amenorrhea. 


Athletes: Due to the strenuous nature of training schedules that many athletes have, in addition to the low levels of body fat in athletes, glands found in the brain can react as a result, and can cause changes in their hormone levels. These changes in their hormones can cause these women to not ovulate, which causes these women not to have periods.

Low body weight: Similar to athletes, women with low body weight have low percentages of body fat which causes hormones made in glands within the brain to act differently, which ultimately causes no egg to be released from the ovary (ovulation) and then leads to no period.

PCOS: Polycystic Ovarian Syndrome (PCOS) is a condition that causes many women to have either no periods at all or periods that are more spaced out (meaning that these women may skip months for their periods). It happens to be very common among women (about 10% of all women are affected by it!). 

The exact reason why some women have PCOS isn’t totally clear. What also makes this condition even more challenging to understand is that the medical community , doesn’t fully understandPCOS either But don’t be alarmed! We know how to manage symptoms, and  we do know that there is usually a hormonal imbalance that can cause an increase in male hormones in women, which often causes no or irregular ovulation (so skipped or no periods) and other symptoms, like facial hair and acne. If you would like to know more about PCOS, there will be an article about it coming soon! 

Thyroid: Your thyroid is a gland that is found in your neck that secretes hormones that affect your metabolism. Your thyroid hormone can also have an impact on your period – in fact, if you have low thyroid hormone levels causing you to have skipped periods or no periods at all.

Pregnancy: Like I mentioned in the first article of the menstrual cycle series, your period is only a part of a larger ovulatory menstrual cycle. In that first article, I explained to you what happens when that egg doesn’t meet sperm. But what if that egg meets her soulmate? Well, the egg gets fertilized, in other joins together with that sperm and becomes an embryo. That embryo can end up attaching itself to the lining of the uterus. Usually at this point, we just focus more on the fact that, “holy crap, I’m pregnant! “

The actual reason you lack a period during pregnancy is that when the egg gets fertilized, that embryo quickly starts to secrete hormones that interact with female hormones which causes no further ovulation. Why? Because it is an evolutionary way to make sure that all of the focus of your reproductive organs turn to this newly developing pregnancy. 

Medication: One of the most common reasons women may skip their period or not have them, is medication. The most common category of medication that causes skipped periods are hormonal contraception. Most notably, birth control pills and progestin containing intrauterine devices (IUDs). 

Often times, these medications are used with the desired effect of causing a woman to skip her periods or not have periods at all (in addition to keeping you from getting pregnant). It is important to discuss with your medical provider  if you are having skipped periods or no periods at all after starting a new medication.


So how do you know if one of the above hormonal culprits is causing your abnormal period? You might be sensing a pattern here, but…see your doctor! They can help you identify what’s going out through talking about your symptoms,  a physical exam, ultrasound, and bloodwork. 

If your period doesn’t fall within the above time frame and it’s rather absent, I want to shed some light on some of the most common issues surrounding this. It’s really important you see your doctor to address any of your concerns, but If you have any questions or just want to connect, don’t hesitate to reach out!