The structure of mucus throughout the menstrual cycle can be very informative for women.
When the female body is in the most fertile days of the month, right in the ovulatory period, estrogen concentrations increase. This change in hormone concentration causes changes in the structures of the cervical mucus, making it more fluid and transparent. The cervical mucus flow in the fertile period has a texture reminiscent of egg white.
The less fertile days of the menstrual cycle include the period before and after ovulation. During these days, the mucus is a compact, dull whitish-white mass that lacks elasticity. This is due to lower levels of estrogen on these days. As a result, this type of cervical mucus offers resistance to the passage of sperm through it.