Light bleeding or spotting or brownish vaginal discharge during pregnancy occurs in about 20% of pregnancies, and most of these women go on to have a healthy pregnancy.

Spotting or bleeding does not always mean miscarriage.

One of the most common cause is Implantation bleeding. 

Implantation bleeding occurs when the fertilized egg implants in the lining of the uterus. This happens around the time of the expected menstrual period. Implantation bleeding may occur before a woman knows she is pregnant. There will be no associated pain and needs symptomatic treatment.