Day 20 of the menstrual cycle
In short: what happens on day 20?
Day 20 of the menstrual cycle is one of the days when, if pregnancy has occurred, the embryo may implant in the lining of the uterus. Some people notice light pink or brown spotting (implantation bleeding) lasting a few hours to 1–2 days. Meanwhile, progesterone approaches its peak.
Day 20 of the menstrual cycle – animated explainer
Day 20: 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
14 mm
Corpus luteum
24 mm
FSH
19
LH
20
Oestrogen
60
Basal body temperature
36.73°C
What is happening in your body today?
The corpus luteum is about 24 mm and produces large amounts of progesterone. The uterine lining is around 14 mm.
Hormones
Progesterone nears its peak; oestrogen rises towards its second peak.
How you might feel
You may have mild cramps, breast tenderness and bloating.
Chance of pregnancy
The chance of pregnancy is very low.
Tips for today
- For the most accurate pregnancy test result, wait until your period is late
- Cutting down on salt eases bloating
- Gentle walks can help
When to see a doctor
See your doctor if spotting turns into heavy bleeding or you have severe one-sided pain.
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
What does implantation bleeding look like?
It is light pink or brown spotting, much lighter than a period, that may appear 6–12 days after ovulation and lasts from a few hours to 2 days. It does not happen in every pregnancy.
When should you take a pregnancy test?
For the most reliable result, test from the day your period is late. A blood beta-hCG test can turn positive 10–12 days after ovulation.
Is lower abdominal pain on day 20 normal?
Mild cramps can occur in the luteal phase. Severe or one-sided pain should be checked by a doctor.
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