Day 27 of the menstrual cycle
In short: what happens on day 27?
Day 27 of the menstrual cycle is the day before your period in a 28-day cycle. Without a pregnancy, progesterone and oestrogen approach their lowest levels and the lining of the uterus is ready to shed. At the same time, FSH starts to rise and stimulates follicles for the next cycle.
Day 27 of the menstrual cycle – animated explainer
Day 27: cycle dial, uterus and ovaries, hormone levels (illustrative animation).
What the animation shows
- FSH
- Follicle-stimulating hormone: starts the growth of follicles in the ovary
- LH
- Luteinising hormone: its sudden surge triggers ovulation
- E2
- Oestrogen (oestradiol): thickens the lining of the uterus
- P4
- Progesterone: prepares the uterus for a possible pregnancy
- BBT
- Thermometer and dots below: basal body temperature
- RING
- Coloured ring: the 28-day cycle and its phases; the green arc marks the fertile days
- MM
- The measurement in the uterus shows lining thickness; in the ovary it shows follicle or corpus luteum size
Phase
Luteal phase
Chance of pregnancy
Very low
Uterine lining
12.5 mm
Corpus luteum
13 mm
FSH
30
LH
15
Oestrogen
22
Basal body temperature
36.55°C
What is happening in your body today?
The corpus luteum turns into a scar-like structure (corpus albicans). The uterine lining is about to shed.
Hormones
Progesterone and oestrogen are low; FSH rises.
How you might feel
Cramps, back pain, bloating and tiredness may become more noticeable; some people start spotting.
Chance of pregnancy
The chance of pregnancy is very low.
Tips for today
- Keep your period products with you
- Light exercise and enough sleep ease symptoms
- Note your symptoms to help track your cycle
When to see a doctor
See your doctor if your periods are very painful, very heavy or irregular.
Menstrual cycle day by day: table
| Day | What happens | Fertile window |
|---|---|---|
| Day 1 | First Day of Your Period | — |
| Day 2 | Heaviest Bleeding Day | — |
| Day 3 | FSH Rises, Follicles Grow | — |
| Day 4 | Bleeding Eases, Oestrogen Rises | — |
| Day 5 | Last Day of Your Period | — |
| Day 6 | Follicular Phase Begins | — |
| Day 7 | Dominant Follicle Is Selected | — |
| Day 8 | Oestrogen Rises, Fertile Window Nears | Low |
| Day 9 | Fertile Window Begins | Moderate |
| Day 10 | Fertile Window, Higher Pregnancy Odds | Moderate |
| Day 11 | 3 Days Before Ovulation | High |
| Day 12 | Oestrogen Nears Its Peak | High |
| Day 13 | LH Surge: Ovulation Is Near | Highest |
| Day 14 | Ovulation Day | Highest |
| Day 15 | Luteal Phase Begins | Moderate |
| Day 16 | Progesterone Rises | Low |
| Day 17 | Luteal Phase and Increased Appetite | — |
| Day 18 | Breast Tenderness May Start | — |
| Day 19 | Implantation Window Opens | — |
| Day 20 | Implantation Bleeding Possible | — |
| Day 21 | Progesterone Peak (Day 21 Test) | — |
| Day 22 | Mid-Luteal Phase | — |
| Day 23 | PMS Symptoms May Start | — |
| Day 24 | Hormones Start to Fall | — |
| Day 25 | Late Luteal Phase and PMS | — |
| Day 26 | Progesterone Drop and Cramps | — |
| Day 27 | 1 Day Before Your Period | — |
| Day 28 | Last Day of Your Cycle | — |
Frequently asked questions
Is spotting before your period normal?
Light spotting 1–2 days before a period is common. If you have prolonged spotting every month, it should be checked by a doctor.
Is day 27 too early for a pregnancy test?
Some sensitive tests may turn positive, but the most reliable result comes after your period is late.
How do you know your period is coming?
Cramps, back pain, breast tenderness, bloating, spots and mood changes are common signs.
Gynaecology check-ups and follow-up at SoftCare Clinic
Book an appointment with our specialist doctors for irregular periods, painful periods or pregnancy planning.
The information on this page is general guidance based on a typical 28-day cycle and does not replace a medical examination. It should not be used as a method of contraception.
Medical content editor: Op. Dr. Şükrü Sanus