Women's Health Basics
The menstrual cycle, contraception, and PCOS — beyond hormone balance
The Hormones chapter covers how oestrogen and progesterone shift across life stages. This chapter goes further into three things that affect a huge proportion of women directly: what a normal cycle looks like, how to think about contraception, and the most common hormonal condition you've maybe never been told about.
The Menstrual Cycle: What's Actually Normal
A cycle length of 21–35 days is considered normal — there is no single 'correct' number, and your own cycle is more informative tracked over months than compared to anyone else's.
- Follicular phase (from the first day of bleeding to ovulation): oestrogen rises, energy and mood typically improve as the phase progresses.
- Ovulation (roughly mid-cycle): a brief fertile window, usually accompanied by a small temperature rise that ovulation-tracking apps and basal thermometers can detect.
- Luteal phase (after ovulation to the next period): progesterone rises then falls if pregnancy doesn't occur, which is what triggers bleeding. PMS symptoms cluster here for many women.
- Tracking your cycle — length, flow, and symptoms — turns it into a genuine vital sign. Persistent irregularity, very heavy bleeding, or cycles outside the 21–35 day range are worth raising with a doctor rather than assuming they're just 'how you are'.
Contraception: Matching the Method to You
| Method | Effectiveness (typical use) | Notes |
|---|---|---|
| Hormonal IUD | ~99% | Lasts 3–8 years depending on type. Often reduces bleeding over time. Requires a clinical procedure to insert and remove. |
| Copper IUD | ~99% | Hormone-free, lasts up to 10 years. Can increase bleeding/cramping, especially in the first few months. |
| Contraceptive pill | ~91–93% | Effectiveness depends heavily on consistent daily use — the gap between 'perfect use' and 'typical use' is larger than for IUDs. |
| Condoms | ~85% | The only common method that also reduces STI transmission — relevant even when another method is used for pregnancy prevention. |
PCOS: The Most Common Hormonal Condition You've Maybe Never Heard Of
Polycystic Ovary Syndrome (PCOS) affects roughly 1 in 10 women of reproductive age, yet diagnosis is often delayed for years. It's diagnosed by a combination of irregular or absent periods, signs of elevated androgens (acne, excess hair growth), and/or ovarian cysts on ultrasound — not by any single test.
- Insulin resistance is central to most cases — even in women who aren't overweight — which is why diet and exercise changes are a genuine first-line treatment, not just generic advice.
- Irregular or absent periods, unexplained acne or hair growth, or difficulty losing weight despite consistent effort are the most common reasons women seek a diagnosis.
- Lifestyle management (resistance training, protein-forward whole-food eating, sleep) measurably improves symptoms and insulin sensitivity in clinical studies, though it doesn't replace medical management for everyone.
- It's a clinical diagnosis — if the symptoms above sound familiar, the next step is a doctor and bloodwork, not self-diagnosis from a symptom checklist.
Worth raising with a doctor
Periods that stop for more than 3 months without pregnancy, bleeding so heavy it disrupts daily life, or cycles that have changed significantly from your own normal — all of these are common enough to feel ignorable, and specific enough to be worth a conversation.
Key Takeaway
Track your cycle as a vital sign, not just a calendar event. PCOS affects 1 in 10 women and is often missed for years — irregular cycles are worth a clinical conversation, not assumption.
Connections
Hormones
Cycle health, contraception, and PCOS sit on top of the oestrogen and progesterone balance covered in the Hormones chapter.
Heart & Metabolic Health
PCOS is closely tied to insulin resistance — the same metabolic markers covered in this chapter are directly relevant.
When to See a Doctor
Periods that stop, become unusually heavy, or change significantly are specific enough to be worth a clinical conversation.