Bleeding during pregnancy is a common concern for many expectant mothers. Often, it can be a normal part of the body’s changes. However, in some cases, it may signal a serious condition requiring immediate medical attention. This article provides a clear and simplified overview of the possible causes of bleeding during pregnancy and when to consult a doctor.

What Causes Bleeding During Pregnancy?

Bleeding in Early Pregnancy (First Trimester)

Up to a quarter of pregnant women experience light spotting or bleeding in the first three months. While it is in most cases not a cause for concern, it’s still important to inform your doctor about any bleeding, as it can sometimes indicate more serious issues. (1)(2)

Common causes include

1. Implantation Bleeding: Light spotting may occur 6–12 days after conception as the fertilized egg attaches to the uterine lining. This is a normal early sign of pregnancy.

2. Hormonal Changes: Natural hormonal shifts during pregnancy can lead to light spotting.

3. Changes in Your cervix: The cervix becomes more sensitive during pregnancy, making light bleeding possible after medical exams or sexual activity.

4. Ectopic Pregnancy: A dangerous condition where the fertilized egg implants outside the uterus, often in the fallopian tube. The first warning signs of this condition are usually light bleeding and pelvic pain.

5. Molar Pregnancy: A rare condition where abnormal growth forms instead of a healthy fetus. This requires immediate medical attention to remove it.

6. Subchorionic Hemorrhage: Blood pooling between the gestational sac and uterine wall. Small hemorrhages often resolve naturally, while larger ones may require close monitoring.

7. Cervical Polyps: Benign growths on the cervix can bleed due to increased estrogen levels.

8. Infections: Vaginal or urinary infections, or sexually transmitted infections, can cause light bleeding and require treatment with antibiotics or other medication according to infection type.

9. Miscarriage: Often begins with light bleeding that worsens over time, accompanied by cramping or pelvic pain.

Bleeding in the Second or Third Trimester

Bleeding later in pregnancy is less common (occurring in 1–2% of pregnancies), (2)  but more likely to signal serious issues. (3)

Possible causes include:

1. Changes in Your cervix: As in early pregnancy, the cervix may bleed lightly after exams or intercourse.

2. Infections: Infections of the urinary or reproductive systems can also occur in later pregnancy.

3. Placental Abruption: A medical emergency where the placenta detaches from the uterine wall, causing severe pain and bleeding.

4. Placenta Previa: When the placenta covers or is too close to the cervix, it can cause heavy bleeding. If detected early via ultrasound, it often resolves as the pregnancy progresses. Persistent cases may require a cesarean delivery.

5. Labor Signs: The loss of the mucus plug or light bleeding may signal that labor is near, occurring days before or during labor.

6. Vasa Previa: A rare but serious condition where fetal blood vessels run near the cervix. If these vessels rupture, it can result in severe blood loss for the baby, requiring immediate intervention.

How is the Cause of Bleeding Diagnosed?

If you experience bleeding during pregnancy, your doctor may use the following methods to identify the cause: (3)

• Ultrasound: To check the baby’s health and placenta location.
• Pelvic Exam: To assess the cervix.
• Blood Tests: To measure pregnancy hormone levels, and sometimes evaluate for anemia or clotting issues and more.

Accompanying symptoms, like cramps or dizziness, help refine the diagnosis and guide testing.

When to Consult a Doctor?

Notify your doctor about any bleeding during pregnancy, even if it’s light. Seek immediate medical attention for: (1)

• Heavy or prolonged bleeding
• Severe abdominal or back pain
• Dizziness or fainting
• Bleeding containing tissue or blood clots

Even minor bleeding may signal an issue requiring medical care, so don’t hesitate to contact your doctor to ensure your safety and that of your baby.

Summary

• First Trimester Bleeding: is common and often not serious, such as implantation bleeding or hormonal changes. However, it can sometimes indicate serious issues like ectopic pregnancy or miscarriage.
• Later Pregnancy Bleeding: Less common but more often serious, causes may include placental abruption or previa, requiring urgent medical attention.

Always report any bleeding during pregnancy to your doctor, and seek immediate care for heavy or painful episodes.

You and your baby's wellbeing are worth prompt attention!

Our Obstetrics and Gynecology Department offers comprehensive, high-quality care. Our specialized team is ready to support you and monitor your pregnancy with the highest medical standards. Schedule your appointment today!

References

1. ACOG - Bleeding During Pregnancy
2. UpToDate - Evaluation and differential diagnosis of vaginal bleeding before 20 weeks of gestation
3. MSD Manual Professional Edition - Vaginal Bleeding During Late Pregnancy - Gynecology and Obstetrics