Post-Menopausal Bleeding Is UrgentAny bleeding more than 12 months after the last period is post-menopausal bleeding — urgent GP assessment needed to exclude endometrial cancer (uterine cancer). Do not delay.
Causes by Age Group
| Age Group | Common Causes |
|---|---|
| Teenagers (puberty) | Anovulatory cycles — normal; immature HPA axis; hypothalamic amenorrhoea (excessive exercise/low weight) |
| 20–35 | PCOS, thyroid disease, hyperprolactinaemia, stress, premature ovarian insufficiency |
| 35–45 (perimenopause) | Declining ovarian reserve; anovulatory cycles; irregular oestrogen |
| Post-menopausal (>1 yr post) | URGENT: exclude endometrial cancer, atrophic vaginitis, polyps |
Blood Tests for Irregular Periods
- TSH — hypothyroidism and hyperthyroidism both disrupt periods
- FSH + LH — high FSH suggests ovarian insufficiency or menopause; LH:FSH >2 suggests PCOS
- Prolactin — high prolactin (e.g. from pituitary adenoma) inhibits ovulation
- Oestradiol — low in POI and hypothalamic amenorrhoea
- Testosterone + DHEAS — elevated in PCOS, CAH
- Progesterone (day 21 of 28-day cycle) — <20 nmol/L suggests anovulation
- Pregnancy test — always first!
Day 21 ProgesteroneA day-21 serum progesterone is the standard test to confirm ovulation. Level >25 nmol/L confirms ovulation; <20 nmol/L suggests anovulation. Adjust timing based on cycle length (7 days before expected period).
How many days late before periods are considered irregular?
A menstrual cycle length varies ≤7 days month-to-month in most women. If cycles vary by more than 7–9 days, or if there are periods where you skip a month entirely, further investigation is warranted.
Can stress stop your period?
Yes — the hypothalamic-pituitary-ovarian (HPO) axis is sensitive to psychological and physical stress. Severe stress, significant weight loss, or overexercise (hypothalamic amenorrhoea) can suppress GnRH and stop ovulation.
What is premature ovarian insufficiency (POI)?
POI is the cessation of normal ovarian function before age 40. It affects ~1% of women. It causes irregular periods leading to amenorrhoea, low oestrogen, and fertility issues. HRT is recommended until the natural age of menopause.
Can I get pregnant with irregular periods?
Yes, but conception may be more difficult if cycles are irregular because ovulation is unpredictable. Tracking basal body temperature, ovulation predictor kits, and addressing the underlying cause (e.g. thyroid disease, PCOS) improve fertility.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.