Hi Laura,
This happened to me with one of my pregnancies. I started bleeding, and of course i panicked! I was pregnant with twins, so I rally had reason to worry. I went to the doctor, and she did an ultrasound, and checked me over. Everything seemed to be fine. Well, it turns out that was the onset of an infection called bacterial vaginosis that eventually caused the prmature rupture of my amniotic sac, and my twins were born at 20 weeks, and neither one survived.
We had a really hard time with this. Since then, I've had 3 pregnancies, one lost due to an early miscarriage, the other two resulting in two healthy boys...one is 9 months, and the other one is due in about 5 weeks. My doctor watched me closely with these pregnancies, and this infections has popped up in both pregnancies, but I am aware of the signs this time, and I was treated PROMPTLY with antibiotics, which cleared the problem.
I am not trying to make you fearful, but I just wanted to make you aware of another possibility. It is terrible to lose a baby. I still miss those little boys so much. Good luck to you, and congrats on your first!
K.