The luteal phase is the second half of the menstrual cycle, beginning after ovulation and ending just before the next menstrual period.
- It typically lasts 12–14 days, though a range of 10–16 days is considered normal.
- The name comes from the corpus luteum, a temporary endocrine gland formed from the follicle that released the egg.
🧬 What happens during the luteal phase:
| Phase Event | Physiological Process |
|---|
| 🟠 Ovulation | An egg is released from the ovary. |
| 🟡 Corpus luteum formation | The emptied follicle transforms into the corpus luteum, which secretes hormones. |
| 🔁 Hormone production | The corpus luteum produces progesterone and some estrogen, preparing the uterine lining for potential implantation. |
| 🧸 If fertilization occurs | An embryo may implant during this phase, prompting the release of hCG to sustain the corpus luteum. |
| ❌ If fertilization does not occur | The corpus luteum degenerates, progesterone levels fall, and menstruation begins. |
🔍 Importance of the luteal phase:
- Ovulation has already occurred, so the fertile window is closed.
- The uterine lining is maintained in preparation for a potential pregnancy.
- A short luteal phase (less than 10 days) may indicate a hormonal imbalance and can interfere with implantation.
- Progesterone is the dominant hormone during this phase and may cause symptoms such as:
- A measurable increase in basal body temperature
- Breast tenderness
- Mood changes or fatigue
✅ Summary Table
| Aspect | Details |
|---|
| Timeframe | After ovulation to start of menstruation |
| Typical length | 12–14 days |
| Key hormone | Progesterone |
| Ends with | Onset of menstruation (unless pregnancy occurs) |
| Critical functions | Supports potential implantation and pregnancy |
