Bleeding in your first trimester can be scary and your first thought might be that you're having a miscarriage, but that's not necessarily the case. While it's important to call your doctor, it's just as important to first sit down, relax and breathe for a minute. About 20 to 30 percent of women experience bleeding in the first trimester, but only about half of this number actually miscarry.
So what else could it be? If it's the week or two after conception likely occurred, it may be implantation bleeding. This happens when your little fertilized (yay!) egg starts burrowing into your uterus and getting ready to grow. Since the uterine lining is rich with blood some women spot a little at this point. Light spotting can happen anywhere from a few hours to a few days and is totally normal.
Since your cervix is especially sensitive right now, you might notice bleeding after sex. If this happens, wait to have sex again until you've spoken with your OB. (But not because sex can cause miscarriage—it can't! Because your doctor can help you avoid further irritation.) Bleeding can also be a sign of infection in your pelvic cavity or urinary tract, or it may simply be a result of the increased blood flow to your cervix.
That said, you always want to call your doctor whenever you notice bleeding. Though many times it's nothing to be too concerned about, it could be a sign of ectopic pregnancy, molar pregnancy or miscarriage. No matter what the cause, though, our initial recommendation stands—sit down and take a deep breath. Worrying won't change a thing.