Implantation bleeding is bleeding or spotting that occurs very early in pregnancy, usually before you even know you're pregnant. It's a fairly common phenomenon.
The bleeding occurs as the fertilized egg implants itself into the lining of the uterus and starts to construct the placenta and embryo. Typically, it lasts one to three days, but it can last up to a week. Implantation bleeding typically occurs just before or around the time a period would be expected, so it can be difficult to tell if you're having your period or spotting.
Here's how to tell the difference: Implantation bleeding is typically not heavy, and there are typically not cramps associated with it. If you have a day or two of spotting in the week before your period is due, take a home pregnancy test. If it's negative, wait a few days or a week and try again.
You should see your doctor if you already have a positive pregnancy test, you're pregnant and have not yet had an ultrasound, or if the bleeding is associated with abdominal pain, light-headedness, or dizziness – please see your doctor right away.
Implantation bleeding is pretty common. While it's true that bleeding can be a sign of impending miscarriage, many women spot for no apparent reason during their first trimester and go on to have a perfectly normal pregnancy.
Video production by Paige Bierma.