Common Cycle Length Variations and What They Mean

When it comes to menstrual health, most people are taught that a "normal" cycle is 28 days. But in real life? The 28-day cycle is more like a textbook average than a gold standard. Many cycles are longer, shorter, or vary slightly from month to month, and often that’s completely fine.

Understanding your unique cycle length, and how it might change over time, is one of the best ways to tune in to your hormonal health. In this article, I'll explore common cycle length variations, what they might mean for your body, and when to dig deeper.

First, What Exactly Is a Cycle?

Your menstrual cycle is counted from Day 1 of your period to the day before your next period starts. It includes four hormonal phases:

1. Menstruation (your period)

2. Follicular phase (before ovulation)

3. Ovulation

4. Luteal phase (after ovulation)

A cycle is considered regular if it follows a consistent pattern for you, even if it's not exactly 28 days.

What’s Considered a Normal Cycle Length?

A healthy menstrual cycle typically ranges from 21 to 35 days in adults, and from 21 to 45 days in teens. That said, consistency is often more important than exact length.

• A 25-day cycle that shows up like clockwork each month? Usually no cause for concern.

• A cycle that ranges from 27 to 34 days? Might still be normal for you.

• A cycle that swings from 21 to 45 days? That’s considered irregular and may need some attention.

Short Cycles (21 days or fewer)

If your cycle is consistently on the shorter side, here’s what might be going on:

1. Short follicular phase

Your body may be rushing to ovulate, which can happen if oestrogen rises very quickly. This is common in:

• Perimenopause

• Stressful seasons of life

• People with lower oestrogen reserves

2. Luteal phase defect

Sometimes cycles seem short because the second half (luteal phase) is too short — often less than 10 days. This may be a sign of low progesterone, which can make it harder to maintain a pregnancy.

3. Hypothyroidism or adrenal issues

A sluggish thyroid or high cortisol levels can shorten the cycle by interfering with ovulation or luteal stability.

4. Coming off hormonal contraception

Your body might be re-learning how to ovulate after years of suppression, leading to short, anovulatory, or inconsistent cycles.

Long Cycles (35+ days)

Long cycles often mean delayed or absent ovulation. Here’s what might be behind them:

1. Anovulatory cycles

These are cycles where ovulation doesn’t happen at all. You may still bleed (a withdrawal bleed), but you’re missing the hormonal peak of ovulation.

Common causes:

• PCOS or high androgens

• Hypothalamic amenorrhea (often from under-eating or over-exercising)

• Post-pill syndrome

• High prolactin (many causes, such as certain medications or thyroid disorders)

2. Delayed ovulation

Sometimes ovulation just takes longer. This can happen due to:

• Illness

• Travel or jet lag

• Major stress

• Nutrient deficiencies (zinc, B6, magnesium)

If ovulation is delayed, your luteal phase will often still be a consistent 12–14 days long - it’s the follicular phase that stretches.

Irregular Cycles

If your cycle length fluctuates wildly from month to month, that’s a sign that your body is struggling to maintain consistent ovulation. This could be a temporary blip (from stress, travel, or illness), or a deeper pattern like:

• PCOS

• Thyroid imbalances

• Perimenopause

• Adrenal dysregulation

• Nervous system overload

Tracking your basal body temperature and cervical fluid can help determine if and when ovulation is happening.

How to Track Cycle Length

The best way to understand your personal pattern is to track your cycle for at least 3 months. Use a simple app or a paper chart to record:

• First day of bleeding (Day 1)

• Last day before your next period (end of cycle)

• Any spotting, unusual symptoms, or mid-cycle signs (like ovulation pain or discharge)

You can also track your BBT and cervical fluid to confirm ovulation and luteal phase length.

When to Seek Support

Cycle length alone doesn’t tell the whole story but it can give you powerful clues. You might want to reach out to a qualified herbalist if:

• Your cycles are consistently shorter than 21 or longer than 35 days

• You’re trying to conceive and not seeing ovulation patterns

• You’re getting two periods a month or skipping them for months

• You have unexplained fatigue, acne, hair changes, or weight shifts

A hormone-literate herbalist can help identify what’s underneath the surface and work with your body to bring more consistency.

Final Thoughts

Your cycle is like a monthly set of clues from your endocrine system. It doesn’t need to be perfect or exactly 28 days, but it should feel like it has a rhythm.

Start by tracking your own cycle and watching for patterns. It might be a few days longer or shorter than average, and that’s totally okay. The goal isn’t perfection - it’s awareness, and learning to listen to what your body is trying to tell you.

With each month of tracking, you’ll become more fluent in your own hormonal language and that’s where your real power lives.