Understanding Subchorionic Hemorrhage in Pregnancy: Causes & Concerns

Question
Dr.  Rappaport,
Could you help me understand why subchorionic hemorrhages develop early in some pregnancies?  
I have two children from two problem-free pregnancies.  Since my last child was born, I had a m/c with a large subchorionic hemorrhage dx at 6 weeks.  I felt pain and got a sonogram - the embryo was meauring behind and there was the internal bleed.  Follow-up U/S showed low hb and then no hb at 9 weeks.  The odd, one-sided pain continued on and off until two weeks AFTER the D&C when it peaked for couple of hours and I passed a small blood clot.
I am pregnant and have this pain again.  Also, an ultrasound showed a large subchorionic hemorrhage (bigger than the sac) next to a normal-sized and -heartbeating embryo at 5w6d.  I am pessimistic.  Dating ultrasounds of my first two, healthy pregnancies were completely normal.
Could this be a uterine wall problem or some blood clotting problem that developed after my first two pregnancies?
Please share any thoughts you have on this.
Also, my doctors don't believe that taking it easy will  NOT make a difference.  This seems at odds with what most patients are told, although I am not bleeding externally.  What do you think?
Thank you so much.
Melissa

Answer
Usually, subchorionic hemmatomas develop in the developing placenta and do not interfere with the pregnancy at all. You can, of course, have a miscarriage whether you have a subchorionic bleed or not. They are not related. The risk of miscarriage is 15-20% in every pregnancy. There is no way to know if the subchorionic hemorrhage that you had contributed to the subsequent miscarriage. Studies have shown that your activity (bed rest or not) does not make any difference in your recovery. If you feel like staying on bedrest, do so, but it will not make any difference in the outcome. If the fetus has a good heartbeat and is growing adequately, there is an excellent chance that all will be fine.