Brown Spotting in Early Pregnancy: Causes & What to Expect

Question
I am 14 weeks pregnant and for 3 weeks now I have had on again off again dark brown spotting.  My OB says it stems from the placenta meshing into the uterine wall and hitting a blood vessel.  I have had a sonogram every week for a month now and the baby is healthy and is growing right on target with a strong heartbeat.  I am nervous because I am 37 and have had two miscarriages and one live birth.  My doctor does not seem to be concerned, but I can't relax with this going on.  Is this normal and how long does it take to heal?  

Answer
A subchorionic hematoma is merely some sequestration of blood within the folds of the developing placenta as it attaches to the wall of the uterus. It does not affect the baby or the growth of the baby. The bleeding usually gets less and less within a few weeks. Don't worry. As long as there is a good fetal heartbeat and the baby is growing adequately, you need not be concerned.