Fig 2. Profuse cervical mucus

Fig 3. The Billing calendar for charting cervical mucus. The time period marked C is the "fertile period".
In some women, the cervical mucus may prevent the sperm from moving freely into the uterus. Such a barrier may be because of the following reasons:
© Dr. Aniruddha Malpani and Dr. Anjali Malpani www.drmalpani.com
Credits: How to Have a Baby: Overcoming Infertility