What Causes Spotting During Pregnancy?

If you're five weeks pregnant and notice blood in your underwear, you may be feeling worried since spotting in pregnancy can sometimes indicate a miscarriage. But, there is more than one possible reason for spotting during early pregnancy, and it's actually quite common. Spotting or light bleeding in early pregnancy occurs for nearly one-third of all parents-to-be and often poses no threat to the pregnant person or baby.

"The vast majority of spotting is harmless," says Alyssa Stephenson-Famy, M.D., Maternal-Fetal Medicine Specialist at the University of Washington, Seattle. But since bleeding, no matter how scant, can be indicative of a variety of complications, including miscarriage, ectopic pregnancy, and placenta previa, it shouldn't be ignored. Plus, it can be pretty unnerving to experience, so you should know you can always reach out to a health care provider when you are having any symptoms you're unsure about it.

Ahead, learn more about the various reasons you may experience spotting during pregnancy, and when you should reach out to a health care provider.

Spotting During Pregnancy Before 20 Weeks

Doctors estimate that 25% to 40% of pregnant people will experience some kind of vaginal bleeding or spotting during early pregnancy, and more often than not, the pregnancy will progress totally normally, Dr. Stephenson-Famy says. There are a number of possible benign causes of spotting or bleeding in the first half of pregnancy, including:

• Implantation bleeding: After fertilization, pregnancy officially begins when the egg implants in the lining of the uterus. Sometimes this process causes a small amount of spotting or bleeding, known as implantation bleeding, and it's nothing to worry about. If you notice a small amount of bleeding about a week to 10 days after ovulation (around the time of your missed period), implantation is likely the cause.
• Sexual intercourse: During the second trimester, your cervix becomes swollen because of the increased blood supply in the area. As a result, vaginal penetration—whether with a penis, finger, or toy—may cause some light spotting during pregnancy.
• Infections: Some people can experience cervical bleeding because of an infection like chlamydia. In these cases, the underlying condition needs to be treated, so you will most likely need antibiotics from your doctor.
• Internal exam done by your obstetrician or midwife: It's not uncommon to bleed after a Pap smear or pelvic exam, which in many practices is conducted between the sixth and 12th week of pregnancy. Spotting may occur within 24 hours after the visit and usually goes away within a day.

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

• Subchorionic hemorrhage: Subchorionic hemorrhage is bleeding around the placenta. Although it is possible to continue with a healthy pregnancy after this type of bleeding occurs, prompt diagnosis and treatment are 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: A pregnancy is referred to as a chemical pregnancy when an egg is fertilized but never fully grows and develops. You can still get a positive pregnancy test, but chemical pregnancies result in a very early miscarriage, sometimes even before a missed period.
• Miscarriage: Miscarriage is the general term for the spontaneous loss of a pregnancy in the first 20 weeks. Often, the bleeding or spotting that occurs during a miscarriage (either threatened or imminent) will be accompanied by other symptoms, such as cramping or abdominal pain.
• Ectopic pregnancy: Ectopic pregnancy occurs when a fertilized egg implants somewhere other than the uterus, most often in a fallopian tube. It often causes bleeding. Sometimes called a tubal pregnancy, an ectopic pregnancy cannot progress normally and may be life-threatening to the pregnant person if left undiagnosed and untreated.
• Molar pregnancy: A molar pregnancy is a nonviable pregnancy that develops into a non-cancerous tumor in the uterus. Vaginal bleeding is a symptom of a molar pregnancy.

Spotting During Pregnancy After 20 weeks

Although the risk of pregnancy loss (known as 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 or spotting during the second half of pregnancy should be taken seriously, especially if it's ongoing, Dr. Stephenson-Famy says.

Causes for vaginal spotting or bleeding in the second half of pregnancy include:

• Sexual intercourse
• Cervical checks, especially late in the third trimester when they commonly become more frequent
• Placenta previa, which is when the placenta covers the cervix either partially or completely
• Placental abruption, which is when the placenta starts to come away or fully comes away from the wall of the uterus
• 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.

When Is Bleeding or Spotting During Pregnancy Serious?

Vaginal bleeding during pregnancy isn't uncommon and doesn't always mean something is wrong. When determining the seriousness of the bleeding you're experiencing, it's important to pay attention to the qualities of the bleeding and other symptoms that accompany it, such as:

• Pain
• Any cramping or contractions
• How heavy the bleeding is
• If the bleeding is getting worse
• If there is any fluid or other discharge
• If you have a fever
• The color of the blood (such as bright red vs. brown or pink)

When to Call a Health Care Provider About Bleeding or Spotting During Pregnancy

The answer to this is: always. If you're experiencing any bleeding during pregnancy (and especially if you have other symptoms, such as a fever, cramps, or pain), call a health care provider right away to be safe, as any vaginal bleeding during pregnancy can be a symptom of a larger problem. Even if there is nothing to worry about, consulting your health provider can still give you reassurance and prepare you for the next steps.