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How and Why to Track Your Menstrual Cycle

A shortening in cycle length is often the first sign that perimenopause has begun. Tracking is the key to seeing this.

How to Track?

Tracking Your Menstrual Cycle

The simplest tracking

The simplest way to track your menstrual cycle is note the day your period starts in your calendar, a note on your phone or in an app. This will allow you to calculate cycle length (see below). Cycle length is one of the first things to change on the path to menopause.

Note: If you are on the pill, have a progestin IUD, or have had an ablation, tracking your menstrual cycles won’t apply — but recording symptoms will still help you learn a lot about what is going on for you.

More involved tracking can tell you if you’ve ovulated and when your period might start

Your overnight body temperature called Basal body temperature (BBT) is your body’s temperature fully at rest, the lowest temperature of each day. It can give  you clues about whether you are in the follicular phase or the luteal phase, whether you have ovulated and when your period may start.

The Centre for Menstrual Cycle and Ovulation Research created a metric called quantitative basal temperature (QBT). With this method you use your daily temperature to tell whether you’ve ovulated — if your temperature rises above a 10-day average. Instructions here.

A device that tracks your nightly temperature can tell you when you’ve ovulated. Nina uses an Oura Ring and can see her temperature rise after ovulation. It rises for about 11-14 days (luteal phase). The first morning when she sees her temperature has dropped overnight, her period begins within 24 hours.

temperature rising signals ovulation has occurred

What to track?

Cycle length: The number of days between Day 1 of one cycle and Day 1 of the next.

Symptoms & timing: Take note of the symptoms you’re experiencing and when in your cycle they occur.

Fertility in Perimenopause

Tracking periods, for some, is associated with trying to conceive. So this is a good place to remind you that you can still get pregnant during perimenopause.

Why track? What we’ve learned from our personal data

  • Perimenopause had begun (until last year our cycles were shortening) — it was comforting to know what our new mood and sleep changes were linked to

  • That we are approaching our final menstrual period (in the last year, our cycles have started to lengthen!)— see last bar on each graph below

  • No two of us are alike! The last chart shows the length of our last 50 cycles. Here you see increased variability in more recently cycles.

Graph showing how cycles change as you approach menopause

“When my Ob/Gyn asked me if my periods were regular, I said YES, because I was getting a period each month. It wasn’t until I tracked my cycles that I realized they were shortening. What a relief — what I was experiencing now made sense in light of that!”   — Nina

“Nina and I have been recording the first day of our periods for many years, but we weren’t doing anything with the data. When we went back to calculate cycle lengths and look at trends over time, we were surprised at what we found.”  — Jo

Updated September 2023

Cycle lengths begins to vary more as you get closer to the final menstrual period.

Read about the benefits of tracking symptoms here:

What We Learned from Tracking Symptoms