Bleeding During Pregnancy: What's Normal, What's Not

Any type of bleeding is terrifying during pregnancy, even for the most level-headed mom-to-be. The good news: Although spotting occurs in nearly one-third of all pregnancies, it often poses no threat to mom or baby. It's common for a small percentage of pregnant women to have spotting after intercourse, for example, and others may have bleeding for reasons that have nothing to do with pregnancy, such as infections or tears to the vaginal wall. "The vast majority of spotting is harmless," says Alyssa Stephenson-Famy, M.D., Maternal-Fetal Medicine Specialist at the University of Washington, Seattle. But bleeding, no matter how scant, can be indicative of a variety of complications, including miscarriage, ectopic pregnancy, and placenta previa, and thus should never be ignored. Here are the various reasons you may experience bleeding during your pregnancy, as well as tips for effectively communicating your symptoms to your ob-gyn.

The First 20 Weeks

Doctors estimate that 25 to 40 percent of women will experience some vaginal bleeding during the first trimester of their pregnancy, and more often than not the pregnancy will progress totally normally, Dr. Stephenson-Famy says. According to the American Pregnancy Association, there are a number of possible causes of innocuous spotting or bleeding in the first half of pregnancy, including:

- Implantation bleeding, which occurs about 4 weeks into your pregnancy as the fertilized egg attaches to your uterine wall.

- Hormonal changes

- Sexual intercourse

- Infections

- Internal exam done by your obstetrician or midwife

Sometimes bleeding during the first half of your pregnancy can be a sign of a more serious condition, however, such as:

- Subchorionic hemorrhage, which is bleeding around the placenta. Although it is possible to continue with a normal pregnancy after this type of bleeding occurs, prompt diagnosis and treatment is vital. "Most subchorionic hemorrhages resolve, but it does put the woman at an increased risk for other complications such as preterm labor," Dr. Stephenson-Famy says.

- Chemical pregnancy, which occurs when an egg is fertilized but never fully implants in the uterus.

- Miscarriage (either threatened or imminent), which is the spontaneous loss of a pregnancy in the first 20 weeks. Often, the bleeding or spotting that occurs during a miscarriage will be accompanied by other symptoms, such as cramping or abdominal pain.

- Ectopic pregnancy, which occurs when a fertilized egg implants somewhere other than the uterus, most often in a fallopian tube. Sometimes called a tubal pregnancy, an ectopic pregnancy cannot progress normally and may be life-threatening to the mother if left undiagnosed.

- Molar pregnancy, a nonviable pregnancy characterized by an abnormal growth on the placenta, and, usually, an abnormal fetus.

Bottom line: Any vaginal bleeding during pregnancy can be a symptom of a larger problem, so it's important that you call your doctor right away. Be prepared to give information about the amount of blood you've lost and a description of how you're feeling overall, advises Laura Riley, M.D., author of Pregnancy: The Ultimate Week-by-Week Pregnancy Guide.Dr. Riley says you should insist on being seen if you have any vaginal bleeding that makes you feel faint or soaks through a sanitary pad. You should also be seen if the bleeding is persistent or accompanied by pain or a fever.

The Last 20 Weeks

Although the risk of miscarriage (known as a stillbirth after the first 20 weeks) diminishes greatly after the first trimester, and many of the early complications are no longer a factor (such as ectopic and molar pregnancies), bleeding during the second half of pregnancy should be taken very seriously, especially if it's ongoing, Dr. Stephenson-Famy says. Causes for bleeding in the second half of pregnancy include:

- Sexual intercourse

- Cervical checks, especially late in the third trimester when they become more frequent

- Placenta previa, which is when the placenta covers the cervix either partially or completely

- Placental abruption, in which the placenta tears away from the wall of the uterus, can cause severe vaginal bleeding and is life-threatening to both Mom and Baby. According to the American Academy of Family Physicians, a placental abruption is the most common cause of serious bleeding during late pregnancy. The condition is rare, and occurs only in about one percent of all pregnancies.

- Preterm labor, in which vaginal bleeding is accompanied by cramping or contractions, diarrhea, pelvic pressure, or back pain before 37 weeks, could have serious repercussions for the baby if not managed. After 37 weeks, these symptoms could be a normal start to labor.

Bottom line: No matter when it occurs, any bleeding during pregnancy warrants a phone call to your doctor or midwife, even if only to confirm nothing is amiss. Be prepared to answer detailed questions about the color, amount, and timing of blood in order to best help your practitioner determine the possible cause.