A student investigated the hormone levels of a healthy female volunteer over a 28-day period. The table below shows the concentration of oestrogen in her blood at different stages of her menstrual cycle.
| Days in the menstrual cycle | Oestrogen level (pmol/L) |
|---|---|
| 1–5 | 115 |
| 6–12 | 290 |
| 13–15 | 820 |
| 16–23 | 440 |
| 24–28 | 150 |
Describe the changes in oestrogen levels during the 28-day cycle.
