Most pregnancies end happily with the birth of a healthy baby.
However, about 10 to 15 percent of pregnancies end in a premature delivery or miscarriage during the first 20 weeks. Usually, a miscarriage happens because the pregnancy was not developing normally. There is no way of knowing exactly what causes a miscarriage. The chances of miscarriage are higher for women who smoke, are seriously ill, or have female organ infections. Signs of miscarriage include bleeding from the vagina and belly cramping.