First, read the English article below.

Cervical mucus, a protective substance on the cervix, changes at different points in your cycle. Your body produces more mucus right around the time of ovulation to help facilitate the fertilization of the egg. Once you get to know your pattern well, it’s possible to use it to predict the day you will ovulate. To learn how to check your mucus, see  How to Check Cervical Mucus. Check your mucus every day after your period ends, and note the distinct changes that take place over the course of your cycle. Keep track of the changes on a calendar.  Chart the days when you have your period, dry days, and days when your mucus is tacky, sticky, slippery, and wet. Note changes in color and smell in addition to texture. Note whether the mucus is cloudy or clear. Keep as thorough a record as possible, especially in the first few months when you’re still getting used to this method. Breastfeeding, infections, certain drugs, and other circumstances can affect the cervical mucus, so be sure to note these factors as well. The day of ovulation is usually the day when cervical mucus is most wet and slippery. In the days that follow that peak, especially when the cervix is dry again, fertility is at its lowest. 

Now, please write a short abstract for it in Vietnamese. Abstract:
Vai trò của dịch nhầy tử cung. Xây dựng đồ thị về dịch nhầy tử cung. Phân tích cách thức thay đổi của dịch nhầy để xác định ngày rụng trứng.