Is Bleeding Normal in the First Trimester of Pregnancy?

When the fertilized egg implants in the uterus, it can cause light spotting that doesn't last very long. Implantation bleeding occurs so early in the pregnancy--generally about Day 10 to 14--that many women are not even aware they are pregnant and believe it to be an early, light period.

During the first trimester, the cervix begins to close and in some cases might squeeze out any residual blood--generally spotty and brown--left from a previous period. Increased blood flow to the cervix during pregnancy makes it more susceptible to injuries, including irritation from sexual intercourse or after a pelvic exam.

According to the Mayo Clinic, up to 15 percent of known pregnancies end in miscarriage. Bleeding is one of the first signs of miscarriage. Sometimes a woman carrying multiples might miscarry one of the babies and carry the other(s) to term. This bleeding is generally heavier and might be accompanied by cramping.

In some cases, a fertilized egg implants outside the uterus. An ectopic pregnancy occurs when it implants in one of the Fallopian tubes. As the embryo grows, it causes the tube to rupture. These pregnancies can't result in a healthy delivery and can be life-threatening to the mother. Ectopic pregnancies can cause abdominal pain in addition to the bleeding.

In some cases, the fertilized egg doesn't form into a baby and a mass of tissues implants instead. Bleeding is a sign of a molar pregnancy.

Infections in the pregnant mother's cervix can cause bleeding. Some of these infections are caused from hormonal changes in the mother, the presence of yeast or a sexually transmitted disease.