- Both oestrogen and progesterone play a role in delaying the onset of the fertile window during the first week of the menstrual cycle by affecting cervical mucus secretion.
- In an observational study of 88 women, findings showed that low oestrogen and high progesterone levels negatively influenced mucus secretion, thereby delaying fertility signs.
- The study highlighted that increased oestrogen concentrations significantly raised the chances of entering the fertile window, while higher levels of progesterone were associated with decreased fertility odds.