Ovulation is a natural part of women’s health. Usually, if you are getting a period, and aren’t on hormonal contraception of any kind, you are ovulating. Most of the time. But sometimes, a woman may experience what is called an anovulatory cycle. It means you have a bleed that you might think is your period, but because ovulation never actually happened, it isn’t true menstruation.
So why do anovulatory cycles happen, and how can we spot them? Are they problematic and do they need medical attention?
The difference between menstruation and withdrawal bleed
True menstruation always follows ovulation, usually about two weeks later. A bleed that occurs without ovulation happening prior is called a withdrawal bleed. It generally comes from low or persistent levels of estrogen and either low or non-existent levels of progesterone.
Let’s break down the various scenarios in which women may experience anovulation by exploring the situations of a few different scenarios.
Anovulation due to stress
Let’s imagine a young woman named Annie who is not on any form of hormonal contraception, whose cycles are mostly regular, and who is an undergraduate student. One month, right before exams and while she is navigating finding a new roommate, she has what she thinks is a period. This bleed is much lighter than usual. What Annie doesn’t know is that this is actually a withdrawal bleed. In all the stress of wrapping up end-of-semester projects and finding a new roommate, her body surreptitiously “skipped” ovulation this month.
What’s happening to Annie hormonally? The stress she experienced actually “sent” a signal to her ovaries to halt follicle production this month. In a normal cycle, not just one follicle is recruited—there are actually a few “waiting in the wings”—and a dominant follicle is eventually chosen to release an egg. But when a dominant follicle isn’t chosen due to an acute stress situation, the aspiring follicles may hang around waiting patiently, releasing small amounts of estrogen.
In response to low levels of estrogen, the endometrium (the lining of the uterus) thickens, but only slightly. A couple of weeks later, and despite ovulation not having taken place, the endometrium sheds. This is partly an immune response to prevent unnecessary endometrial build-up without any prospects of a fertilized egg coming to burrow into it anytime soon. And because the estrogen levels were low, the resulting bleed is light.
Annie’s anovulatory cycle is not concerning, but rather an acute response to an acute situation. It is likely her regular cycles will return once exams are over and she finds a new living situation—in other words, once her short-term season of high stress is over.
Anovulation from perimenopause and other transitional seasons
Now let me introduce Nina. Nina is a mom of three, and while she has mostly regular cycles, they seem to be spread farther and farther apart since about last year. She is in her early forties and swears she’s way too young for menopause.
While early forties is certainly young for menopause, it’s not too young for perimenopause, which can be an entire decade before the actual cessation of cycles, which is menopause. Nina suspects she is no longer ovulating, but her periods are equally as heavy as years prior and sometimes even heavier.
Hormonally, Nina is not ovulating due to fluctuating levels of hormones. Her estrogen levels may still be relatively high, but not high enough to release an egg. And those high levels simmer for a long enough time to allow the endometrium to build up. But alas, no egg comes, and eventually when estrogen realizes it’s not going to get high enough to lead to ovulation, the body decides again to shed the endometrium.
While perimenopause is a totally normal part of the reproductive spectrum, Nina may want to work with a practitioner to deal with symptoms that often arise from high and persistent levels of estrogen—such as insomnia, hot flashes, metabolism changes, and headaches.
Anovulation on the birth control pill
Now, let’s look at Camilla. Camilla is in her early thirties and is on the combination pill, which includes both artificial estrogen and artificial progesterone, known as progestin. She gets a small, daily dose of both of these synthetic hormones when she takes her pill every morning. But the levels are far lower than what her body would be naturally making (and the hormones themselves are not bio-identical either).
Every three weeks, she takes a “placebo pill” which is essentially a sugar pill that contains no hormones. The bleeds Camilla experiences while on the placebo pill are light—and they are not actually periods, as Camilla isn’t ovulating due to her birth control.
In a sense, Camilla is in a similar boat to Annie—but Camilla’s is synthetically induced. The combination pill she is on sends a negative feedback to her pituitary gland to stop endogenous (natural) production of estrogen and progesterone by giving her body a steady, small dose of artificial estrogen and progesterone. Camilla’s endometrium proliferates lightly because of low levels of synthetic estrogen, and then when the body gets the signal from the sugar pills, it sheds the endometrium.
Anovulation from PCOS and other hormonal disorders
Lastly, we have Tamara. Tamara is in her late twenties and has always had irregular, painful, and long periods. She will go months without a bleed and sometimes has to stay home from work because her cramps are so bad. Tamara also has polycystic ovary syndrome (PCOS) and a host of autoimmune disorders. Some bleeds are light and others are intolerable.
Tamara has a similar hormonal situation to Nina, but Tamara’s is not related to a stage of the reproductive spectrum. In Tamara’s case, it is her endocrine disorders that cause irregular ovulation—and therefore irregular bleeding that sometimes comes from not ovulating at all. High, persistent, unchecked levels of estrogen that don’t lead to ovulation cause lots of endometrial growth, which then causes heavy bleeding, regardless of whether or not ovulation happened.
Tamara’s situation is concerning and warrants discussion with a medical provider. She would certainly benefit from having a practitioner look at her hormone levels and try to evaluate how to manage both her PCOS and her autoimmune disorders. In this case, anovulatory cycles could be causing a lot of other undesirable symptoms for Tamara, such as acne, weight gain, bloating, and PMS—and they are certainly not making her bleeds (ovulatory or not) manageable.
How do you know if you’re ovulating? Distinguishing an ovulatory cycle from an anovulatory one
You might be wondering, “Well, how can I know if I’m having anovulatory bleeds if I’m still getting a bleed each month?” Fortunately, there’s an easy enough answer: It’s all in the cycle charting!
If you are charting your fertility biomarkers to confirm ovulation, you can pretty well determine if you had a menstrual bleed or an anovulatory one. This is just one more reason to love fertility awareness methods (FAM). Fertility awareness methods give an insight into what is going on hormonally, and when you should be concerned and seek medical care.
In conclusion, anovulatory cycles can be biologically normal, indicative of other hormonal disturbances in the body, or induced artificially by hormonal contraception. When it comes to identifying the cause of one’s particular anovulatory cycles, the most important piece is having cycle charts to distinguish why they might be occurring.
While anovulatory cycles alone aren’t necessarily immediate cause for concern, by having the bigger hormonal picture, you can pull apart the nuances and feel more confident in your decision-making with your practitioners.
When this article refers to fertility awareness methods (FAM), or natural family planning (NFP), we are referring to Fertility Awareness-Based Methods, evidence-based methods of cycle charting which can be used as effective forms of natural birth control when learned by a certified instructor.