How Stress can Wreak Your Menstrual Cycle

May is Women’s Health Month, and it’s also Mother’s Day soon, so I’ve decided to continue my series on how stress affects our health by focusing on how it affects women’s health, and especially our cycles.

In my last article I talked about what stress really is, how the cycle of cortisol works in the body, and how chronically elevated cortisol has long term effects on our health. Today let’s dive into how stress wreaks havoc on women’s monthly cycle.

First, what does a healthy cycle look like? One that isn’t already dysregulated by stress or suppressed by hormonal birth control.

Our cycles are a delicate dance of hormones. When perfectly in balance it looks something like this:

Dr Jolene Brighten in “Beyond the Pill” describes this process really well.

“Estrogen is the main player in the first half of your cycle. It spikes around days 12 through 14 to trigger the release of luteinizing hormone (LH), which marks the beginning of the ovulatory phase and stimulates your ovaries to release an egg, aka ovulation. It’s during this time that the egg travels down the fallopian tube and either implants in the endometrium if fertilized by sperm or slowly dissolves and passes out of the body, along with the uterine lining, during your period…. Its the predominant hormone during the first half of the cycle, which is known as the follicular phase (approximately days 1 through 14 of your cycle).

The ruptured follicle [which released an egg], now called the corpus luteum, releases progesterone and estrogen to prepare your body for pregnancy. Progesterone is the hormone that helps you feel chilled out and calm and in love with your life [more on this later]… Progesterone is the most prominent hormone from days 15 through 28 of your cycle and peaks around day 21, which is known as the luteal phase.

If egg doesn’t meet sperm, then your hoemones drop and your menstrual cycle starts all over again. But if you do become pregnant, those hormones stay elevated.”

This is a healthy, non-medicated cycle. But what happens when cortisol enters the picture?

In the follicular phase, researches studying the effects of perceived stress on women’s cycles found that those who reported higher stress had lower estrogen, lower LH, and higher follicle stimulating hormone (FSH), suggesting that stress interfered with the body’s signalling to produce a healthy egg1.

Another study followed 1214 women who had experienced prior pregnancy losses through six cycles and assessed their perceived stress levels. Their conclusion was that:

“Preconception perceived stress appears to adversely affect sex steroid synthesis and time to pregnancy. Mechanisms likely include the effects of stress on ovulatory function, but additional mechanisms, potentially during implantation, may also exist.”2

In other words, stress may affect the ability for the body to produce a healthy egg. In fact, the same study suggested that stress can cause us to skip ovulation altogether.

In the luteal phase, the negative effects of stress are often felt more strongly.

If you read the words “Progesterone is the hormone that helps you feel chilled out and calm and in love with your life…” and you snort-laughed or shook your head in disbelief, you already have an idea of what elevated cortisol does during this phase.

This level of chronic stress, and it’s effect on progesterone levels has become so normalized, that we don’t even think twice when we hit our luteal phase and instead of feeling chilled out, calm and in love with our lives, we want to scream, cry, run away, or murder someone — or all of the above!

Researchers have found that acute stress, (tested by putting your hand or arm into ice water for a specific amount of time) actually raises both cortisol and progesterone3, but chronically elevated cortisol has been found to lower progesterone levels in the luteal phase.4

How does stress have such a disruptive effect on our cycle?

Stress and reproductive hormones are managed by two closely connected body systems. One system (The HPA axis: hypothalamus-pituitary-adrenal) helps us respond to stress, and the other (The HPO axis: hypothalamus-pituitary-ovarian) helps regulate the menstrual cycle.

When stress is short-term, this is usually not a problem. But when stress stays high for a long time, the body may begin to prioritize survival over reproduction. Cortisol, one of the main stress hormones, can interfere with the brain’s normal signals to the ovaries.

Ovulation depends on a careful rhythm of messages between the brain and the ovaries. The brain sends out pulsing signals that eventually lead to a rise in luteinizing hormone, or LH. This LH surge is what helps trigger ovulation.

When cortisol remains elevated, those brain signals may become slower or less consistent. If the rhythm is disrupted enough, the LH surge may be weaker, delayed, or absent which can make ovulation less likely or affect the quality of ovulation, the health of the egg, and the quality of the follicle.

Progesterone does not appear after ovulation by accident. It is made by the corpus luteum, the temporary gland that forms from the follicle after the egg is released. That corpus luteum depends on healthy follicle development, a strong ovulatory signal, and rhythmic LH pulses from the brain.

When cortisol stays elevated for long periods, it can interfere with this brain-to-ovary communication. The reproductive signals may become less rhythmic or less robust. Ovulation may be delayed, weaker, or skipped, and the corpus luteum may not receive the same support it needs to produce steady progesterone.

So chronic stress may lower luteal progesterone not because the body is “stealing” progesterone to make cortisol, but because stress changes the signalling environment that allows ovulation and progesterone production to happen well.

I want to return to this idea: when stress stays high for a long time, the body may begin to prioritize survival over reproduction.

To me, this is the key to understanding why chronic stress affects our cycle the way it does.

Dr Stacy Sims, an exercise and physiology researcher talks about how active women can lose their periods (and therefore their cycle balance) in this clip:

Sometimes I think we get so busy treating our body like a machine, pushing, and “bio-hacking”, and forcing this or that result, that we forget we are biological human women.

Our hormones are a delicate balance, and we can push ourselves into survival mode with chronic stress. It doesn’t matter if the stress response (fight or flight) is activated by a stressful job or family situation, or by being too active and not eating enough to support our activity, or by external events beyond our control — like war and natural disasters. The fact remains: if we stay too long in fight or flight, we risk many negative health effects, one of which is the dysregulation of our hormones and our cycle.

If we women do not feel safe (remember, many of the researchers measured perceived stress, not cortisol levels — how we feel matters), if we are constantly under pressure and stressed out, then our hormones can be knocked out of balance, our fertility is then affected, our periods become worse, and that premenstrual time becomes a nightmare.

In my next article, I promise to bring some sunshine and hope back into the picture, because there are things we can do that will positively affect our hormones, that can bring us back from fight or flight, and help us handle the stress we cannot avoid with better resilience. We can gradually bring our nervous system, adrenals, and hormones back into balance, and improve our menstrual cycle and our lives.