Your menstrual cycle: length, changes and patterns

Cycle length, what can shift it, and how to tell the difference between a pattern in your records and a prediction about next month.

A ring of small discs, mostly lilac with short runs of sage and coral, crossed once by a ribbon.

5 min read Can stress delay your period? Sleep and exercise What the evidence says about how stress, sleep and exercise affect your cycle, what low energy availability means, and when to get a missed period checked.
8 min read For teens: seeing a doctor about periods, contraception or sexual health When a period problem is worth an appointment, where to go, what a first visit involves and how confidentiality works for teens in the UK and US.
5 min read How long is a normal menstrual cycle? How to count your cycle, how the NHS and ACOG ranges compare, and when a short, long or changing cycle is worth raising with your GP.
6 min read Irregular cycles: what to log and when to ask How to keep a useful record when your period dates vary, describe changes clearly and know when to get routine or urgent care.
5 min read Irregular periods: causes and when to see a doctor Common causes of irregular periods, from contraception to thyroid problems, with clear advice on when to see a GP or get urgent help.
4 min read Period products, safe use and help with cost Compare pads, tampons, cups, discs and period pants, spot symptoms that need urgent care, and find help getting period products.
6 min read Periods after stopping the pill and other methods What to expect after you stop the pill, patch, ring, implant, hormonal coil or injection, when fertility returns, and when to see a GP.
6 min read Recorded patterns vs predictions How an entry, a pattern and an estimate differ, with a worked example and simple ways to read your own record without reading too much into it.
4 min read The hormones behind your cycle What oestrogen, progesterone, FSH and LH do, why cycle timing varies, and what the evidence says about cycle-syncing claims.
4 min read Vulva and vagina: a plain guide The names for the outside and inside parts, how appearance varies, gentle care, and which changes are worth getting checked.

Written by the Ruva team from the sources listed in each guide. They aren’t medical advice. If you’re worried about a symptom, talk to a doctor, nurse or pharmacist.