Open Splash

Periods, hormones and everything in between, in plain English.

165 short reads, each with its sources underneath, last checked October 2026.

In short: The Splash library is 165 plain-English articles on periods, cycles, fertility, contraception, pregnancy and perimenopause. Each one opens with a quick answer, lists its sources (NHS, NICE, ACOG, WHO and peer-reviewed research) and shows when those sources were last checked. It is written by the Splash team and free to read.

Start here

The four phases, in depthMenstrual, follicular, ovulation and luteal, and what each one is doing.Menstrual and follicular phases overlap: both start on day 1.5 min read →
  1. PCOS (now PMOS): the friendly guideConditions · 6 min
  2. PMDD: when PMS turns the volume to maxConditions · 6 min
  3. What is a normal cycle length?Cycle basics · 4 min
  4. Discharge, decodedBody literacy · 5 min
  5. Breast changes and how to self-checkBody literacy · 5 min

Every topic

  1. Cycle basics

    How your four phases ebb and flow. 16 reads

  2. Period care

    Cramps, products, flow and comfort. 16 reads

  3. Body literacy

    Reading the signs your body sends. 14 reads

  4. Fertility & TTC

    Ovulation, the fertile window, trying. 16 reads

  5. Contraception

    Every method, honestly compared. 16 reads

  6. Sex & relationships

    Pleasure, consent, desire and care. 12 reads

  7. Conditions

    PCOS, endo, fibroids and more. 17 reads

  8. Nutrition

    Eating kindly through your cycle. 12 reads

  9. Movement & sleep

    Training, rest and recovery. 13 reads

  10. Mind & mood

    PMS, PMDD, anxiety and calm. 13 reads

  11. Pregnancy & postpartum

    From test day to the fourth trimester. 16 reads

  12. Perimenopause

    The transition, decoded. 11 reads

  13. Apps & privacy

    Choosing a tracker, what happens to your data, and how accurate apps really are. 5 reads

Your cycle, phase by phase

  1. Menstrual phaseDay 1 of bleeding, usually lasting 2 to 7 days
  2. Follicular phaseFrom day 1 until ovulation; the part of the cycle that varies most in length
  3. OvulationAbout 12 to 16 days before the next period
  4. Luteal phaseFrom ovulation to the next period, roughly 10 to 16 days

Short courses

All 21 courses →
  1. How your cycle worksExplain the four phases to a friend, know what a normal cycle looks like, and know when your cycle is telling you something.6 reads · 25 min
  2. Period pain and heavy periodsEase cramps, tell normal flow from heavy, and know exactly when to talk to a GP and what to say.8 reads · 33 min
  3. Your period toolkitPick the products that suit you, use them with confidence, and handle leaks, nights and workouts.6 reads · 24 min
  4. Mood, PMS and PMDDSee how your cycle shapes your mood, calm a tough week, and spot when it is more than PMS.8 reads · 32 min
  5. Body confidence and being kind to yourselfGet through bloat, spots and low-energy days with less self-criticism and a few habits that help.6 reads · 16 min
  6. Sleep, energy and movementSleep better, move in ways that suit your body, and plan rest and effort around your own energy.8 reads · 22 min

Words, decoded

The full glossary →
LH surge
A sudden rise in luteinising hormone that triggers the ovary to release an egg, usually within about 36 hours.
Luteal phase
The stretch from ovulation to your next period, usually around 10 to 16 days.
Prostaglandins
Hormone-like chemicals that make the womb contract during your period. More of them usually means stronger cramps.
PMDD
Premenstrual dysphoric disorder: a severe, cyclical form of PMS where mood symptoms seriously disrupt life in the luteal phase and ease within a few days of your period starting.

Written by the Splash team from NHS, NICE, ACOG, WHO and peer-reviewed sources. No clinician has reviewed these articles yet, and we say so on purpose. How we write and check · How Splash predicts.

Everything you just read, in your pocket.

Splash has the whole library built in, offline, next to your own cycle. Free to use, no account.

The Splash library inside the app, with article categories.