What Is Bleeding During Pregnancy?

Bleeding during pregnancy is relatively common, particularly during the first trimester. As many as one in three people will experience bleeding during their first three months. Minor bleeding generally isn't serious, particularly if it's not accompanied by pain.

However, major bleeding and painful bleeding may be signs of a serious problem. Therefore, any bleeding during pregnancy should be evaluated by your healthcare professional.

This article will discuss risk factors for bleeding during pregnancy and possible causes of it during each trimester.

Types of First Trimester Bleeding

There are a number of reasons why people experience bleeding during the first trimester. Diagnosing first trimester bleeding usually requires a physical exam, a blood test, and/or sexually transmitted infection (STI) testing.

Repeated blood tests may be used to monitor the changing hCG (human chorionic gonadotropin) hormone levels present during pregnancy to determine if the pregnancy is likely to be viable. The hormone progesterone and Rh factor (Rhesus factor, a protein on the surface of red blood cells giving us a positive or negative blood type) may also be evaluated during the first trimester.

Implantation Bleeding

Implantation bleeding occurs when the fertilized egg attaches to the lining of the uterus. This usually occurs around one to two weeks after fertilization, around 20–24 days into your menstrual cycle.

Implantation bleeding is usually light and may resemble spotting. It may be accompanied by nausea, headache, and other symptoms. Implantation bleeding is normal and is not a risk factor for pregnancy loss.

Miscarriage

Miscarriage is defined as a pregnancy loss that happens before the 20th week of pregnancy. Early pregnancy loss during the first trimester is not uncommon and often reflects chromosomal abnormalities or other problems with the developing fetus. In addition to bleeding, symptoms of miscarriage include strong cramping and passing tissue.

Bleeding during the first trimester does not mean that you will lose your pregnancy. Your doctor will likely perform an ultrasound in addition to testing your blood to see how your pregnancy is progressing.

Ectopic Pregnancy

An ectopic pregnancy occurs when the fertilized egg implants in the fallopian tube or a place other than the uterus. Ectopic pregnancies are not viable. They can lead to severe complications, including death.

Symptoms of an ectopic pregnancy include hCG levels rising more slowly than would be expected for a typical uterine pregnancy. Pregnant people may also experience cramping, shoulder pain, and weakness or dizziness in addition to the expected symptoms of pregnancy.

Ultrasound can be used to diagnose an ectopic pregnancy. Sometimes surgery is needed to examine the fallopian tubes and see where the embryo has implanted. Surgery may also be needed if the fallopian tube has ruptured or is at risk of rupturing. However, many ectopic pregnancies can be managed with medication.

Infection

Sexually transmitted infections and other infectious conditions can cause problems during pregnancy, including bleeding. Diagnosing an infection may require a combination of a physical exam, a vaginal swab, a cervical swab, urine testing, and blood testing.

Types of Second and Third Trimester Bleeding

With certain exceptions, bleeding during the second and third trimesters of pregnancy is more likely to be a concern. One major exception is light bleeding after vaginal intercourse. Changes in the cervix during pregnancy make it more likely to bleed. Therefore, light bleeding after intercourse is not necessarily a concern, but you should still contact your clinician if it occurs.

Placenta Previa

Placenta previa occurs when the placenta—the organ that develops in your uterus to provide oxygen and nutrients to the fetus—covers any portion of the opening of the cervix. It is thought to happen in approximately one out of every 200 full-term pregnancies.

It is more common in people who have had a previous cesarean section (C-section) delivery, as well as those who have had multiple pregnancies, are older, smoke, or have a history of spontaneous or elective abortion.

Symptoms of placenta previa include passing bright-red blood, usually without pain. It is generally diagnosed via ultrasound. A person with placenta previa may require monitoring throughout the pregnancy.

Placental Abruption

Placental abruption is when the placenta starts to separate from the uterine lining before delivery. It is thought to occur in approximately 0.9% of singleton (one fetus) pregnancies in the United States. Common symptoms include bleeding associated with severe abdominal or back pain and contractions.

Placental abruption is more common after trauma and in older pregnant people, those with infections, and those with chronic health problems. The amount of bleeding is not a reliable sign of how serious the separation is. Early delivery is recommended if the fetus is in distress.

Premature Labor

Premature labor is labor that occurs before 37 weeks of gestation. Symptoms of premature labor can include cramps, changes in vaginal discharge, contractions, and ruptured membranes (when the bag of water breaks). There may also be bleeding.

If you are experiencing symptoms of possible premature labor, talk to your doctor. You will likely be examined and given an ultrasound. Several treatment options are available to delay labor and improve the fetus's outcome after delivery.

Vasa Previa

Vasa previa occurs when unprotected blood vessels supplying the fetus are located too close to the cervix. This puts the vessels at risk of rupturing after the membranes rupture.

Vasa previa is extremely rare, occurring in less than one of 2,500 deliveries. Up to one-third of cases detected during pregnancy will require emergency preterm delivery.

If vasa previa is not detected before labor, it can be devastating or even fatal for the fetus. This is because rupture of the vessels can quickly cause the fetus to bleed out.

The classic presentation of vasa previa is painless vaginal bleeding after membrane rupture, along with signs of fetal distress. Emergency C-section followed by fetal resuscitation may be required.

Invasive Placentation

Invasive placentation is an uncommon cause of vaginal bleeding during pregnancy. However, it is a significant cause of postpartum hemorrhage.

It occurs when the placenta embeds too deeply in the uterus, invading the myometrium, the smooth muscle tissue of the uterus. It is more common in people who have had one or more previous C-sections.

Uterine Rupture

Uterine rupture occurs when the wall of the uterus breaks open. This condition is extremely rare. It affects 0.8% of people with previous uterine surgery. It affects only 0.03-0.08% of all delivering patients.

Bleeding and pain may occur with uterine rupture. The fetus's body parts may become easier to feel through the abdomen. Immediate treatment is necessary.

Coagulopathy

Over the course of pregnancy, there are many changes within the body. One of those changes concerns blood clotting. Disseminated intravascular coagulation (DIC) is the technical term for when clotting occurs throughout the body. It can then lead to severe bleeding.

Signs of DIC include bleeding from the vagina as well as other areas, such as the gums, rectum, and skin. People may also experience symptoms of shock. DIC during pregnancy is rare but can be serious and even fatal.

Risk Factors for Bleeding During Pregnancy

Different causes of bleeding during pregnancy have different risk factors. Common risk factors include:

• Older age of the pregnant person
• Previous uterine surgery, including C-section
• High number of previous pregnancies (parity)
• Smoking
• High blood pressure
• History of sexually transmitted diseases
• Chronic health conditions, like diabetes

While some of these risk factors can be modified, others cannot. Still, it's important to do what you can to manage your health both before and during pregnancy. Part of that includes going in for regular prenatal care. Starting prenatal care early will help your provider manage any issues that could put your pregnancy at risk.

Summary

There are many causes of bleeding during pregnancy. You should always contact your healthcare professional to determine whether it is a benign symptom or a sign of serious risk for yourself or your fetus.

In the first trimester, possible causes include implantation bleeding, miscarriage, ectopic pregnancy, and infection. In the second and third trimesters, among the possible causes are placenta previa, placental abruption, vasa previa, preterm labor, or a coagulation disorder.

A Word From Verywell

Bleeding during pregnancy can be frightening. Although it may be tempting to wait and hope that it will stop, it's important to discuss any bleeding during pregnancy with your healthcare provider. Many causes of bleeding aren't serious or can be treated in a straightforward way.

If bleeding during your pregnancy is serious, prompt medical attention is even more important. Early treatment may make the difference between losing a pregnancy and keeping it. It may also save your life. Fortunately, many times bleeding in pregnancy is not life-threatening for you or your baby.