it is normal, I am 22 weeks pregnant and had a mucus like discharge a few weeks ago, the doctor said it is 100% normal as long as there is no color to it (for example, yellow, pink, or brown), if so she needs to talk to the doctor about it. The later into pregnancy you go the more likely it is to get some discharge. Soon before you go into labor you will lose what is called a mucus plug, you should do some research on that, this might be the start of her mucus plug.