Vaginal bleeding during pregnancy has many causes. Some are serious and others are not. Bleeding can occur early or later in pregnancy. Bleeding in early pregnancy is common. In many cases, it does not signal a major problem. Bleeding later in pregnancy can be more serious. Contact your obstetrician–gynecologist (ob-gyn) if you have any bleeding at any time during pregnancy.
What is implantation bleeding?
Implantation bleeding is bleeding that occurs when the fertilized egg implants in the lining of the uterus. This happens around the time of the expected menstrual period. Implantation bleeding may occur before a woman realizes she is pregnant. What are the serious causes of vaginal bleeding in the first trimester of pregnancy?
In an ectopic pregnancy, the fertilized embryo implants outside of the uterus, usually in the fallopian tube. If the embryo keeps growing, it can cause the fallopian tube to burst, which can be life-threatening to the mother. Although ectopic pregnancy is potentially dangerous, it only occurs in about 2% of pregnancies. Other symptoms of ectopic pregnancy are strong cramps or pain in the lower abdomen, and lightheadedness.
Molar pregnancy (also called gestational trophoblastic disease).
This is a very rare condition in which abnormal tissue grows inside the uterus instead of a baby. In rare cases, the tissue is cancerous and can spread to other parts of the body. Other symptoms of molar pregnancy are severe nausea and vomiting, and rapid enlargement of the uterus.