How do you know if you had miscarriage?

Answer 1

The most common symptom of a miscarriage is bleeding; bleeding during pregnancy may be referred to as a threatened abortion. Of women who seek clinical treatment for bleeding during pregnancy, about half will go on to have a miscarriage. Symptoms other than bleeding are not statistically related to miscarriage.1 Miscarriage may also be detected during an ultrasound exam, or through serial human chorionic gonadotropin (HCG) testing. Women pregnant from ART methods, and women with a history of miscarriage, may be monitored closely and so detect a miscarriage sooner than women without such monitoring.1
1. http://en.wikipedia.org/wiki/Miscarriage

Answer 2

If you are suspicious that you may have had a miscarriage, see a doctor immediately. An over-the-counter pregnancy test could still read positive after a miscarriage.