Regular, fairly consistent menstrual cycles are an indicator of healthy hormonal communication between your brain, ovaries, and the rest of you.

Irregular cycles have to do with changes in your overall cycle length, i.e., from day 1 of your period to day 1 of your next period. It does not refer to changes in menstrual flow. It also does not refer to your cycles being a couple of days shorter or longer every now and again.

Irregular cycles typically are a result of irregular ovulation.

That’s because when you release an egg at ovulation time, the sac or follicle that had contained your egg, can only last for a couple of weeks. This structure is called the corpus luteum and its job is to make estrogen and progesterone. After ovulation, your sex hormones go up in case the egg was fertilized and you need to prep for pregnancy. Then, those hormones drop as the corpus luteum starts to shrink when it doesn’t receive feedback that you’re pregnant.

So, your follicular phase, i.e., the part of your cycle before ovulation can be variable. Once you ovulate, though, a period is expected 2 weeks later.

There are exceptions to this, like if you have something called a luteal phase defect in which you don’t make enough progesterone or your uterus isn’t responding to it.

Okay, class, what exactly is an irregular cycle?

There are slightly different definitions based on where in your menstrual journey you are. Times when we kind of expect irregularities include:

• in the twelve months after your first period ever
• in the menopause transition, the years leading up to your final period ever
• when you’re lactating/breastfeeding

Otherwise, this is how we medically define irregular:

• cycles that are <21 days or >45 days apart if you’re 1-3 years out from your first ever period called menarche
• Cycles that are <21 days or >35 days apart, or you have <8 cycles per year if you’re more >3 years out from menarche and also not in perimenopause
• If you’ve had even one cycle that’s gone >90 days once you’re past that first year post-menarche, that’s irregular

There’s a few other criteria, but we’ll leave it at that.

What causes irregular cycles?

There are a few conditions that can cause irregular ovulation and cycles. Some of the common ones are:

• PCOS (polycystic ovarian syndrome, which is the most common cause)
• Thyroid disorders
• Certain meds including hormone-based ones
• Hypothalamic amenorrhea, which often results from prolonged stress, underfuelling, chronic infection, or all of the above
• Hormone-secreting tumours
• Concussions

Remember, you might have a few odd cycles where length changes temporarily because you were travelling or had a bad infection or were super stressed out. This is normal! The body reacts and interacts with everything else. We’re talking about prolonged and persistent irregularities here.

If you’re confused or looking for more support, book an appointment with me, I’m accepting new patients.