Placenta previa

The placenta is an organ that attaches to the wall of your uterus during pregnancy. It connects to the baby through the umbilical cord and supplies oxygen and nutrients and removes wastes. Usually, the placenta attaches to the upper part of the uterus. Placenta previa is when the placenta attaches close to, or covers, the uterus’s opening (the cervix).

Find providers
Find locations

Placenta previa: types and risk factors

Types of placenta previa

There are three types of placenta previa, depending on where exactly the placenta attaches:

  • Marginal placenta previa: the placenta is located very close to the edge of the cervix, but it does not cover the cervix.
  • Partial placenta previa: the placenta is partially covering the cervix.
  • Complete placenta previa: the placental completely covers the cervix.
Smiling pregnant woman in exercise class

Risk factors

Researchers don’t know what causes placenta previa.

However, certain things can increase your risk of having a placenta previa:

  • Being over 35.
  • Being pregnant with a boy.
  • Being pregnant with twins or more.
  • Being of African American or another nonwhite ethnic background.
  • Having had a past pregnancy.
  • Having had a placenta previa with a previous pregnancy.
  • Having uterine fibroids, or non-cancerous tumors.
  • Past uterine surgeries or cesarean deliveries.
  • Smoking cigarettes.
  • Using cocaine.

Consult with your doctor

Just because you have these risk factors does not mean you will have a placenta previa. However, you should follow up with your doctor and seek prenatal care to make sure your pregnancy goes smoothly.

What are the symptoms of placenta previa?

You may not experience placenta previa symptoms. The most common placenta previa symptom is painless vaginal bleeding, which is usually bright red. The bleeding can fluctuate from a light to heavy flow. It occurs most commonly in the third trimester, although it can also happen in the second-trimester. If you experience any bleeding during pregnancy, you should call your doctor. If bleeding is severe, seek emergency medical attention.

Other signs of placenta previa may include:

  • Preterm contractions.
  • Bleeding that starts and stops.
Pregnant woman reading with young daughter

How is placenta previa diagnosed?

Expecting couple at ultrasound session

Even if you do not have symptoms of placenta previa, the condition is usually found during your second-trimester ultrasound. This is a routine check-up that happens between 18 and 22 weeks of pregnancy.

You may receive an abdominal ultrasound, transvaginal ultrasound, or both. In a transvaginal ultrasound, a doctor will insert a wand called a transducer into your vagina. This allows for a different view of the placenta and baby.

In most cases, a placenta previa found in the second trimester will resolve itself. However, your doctor may suggest a follow-up ultrasound to see how your pregnancy is progressing and whether the placenta’s position will pose any issues.

Treatments for placenta previa

Monitoring is key

There is no way to treat placenta previa or move the placenta. Instead, the goal of treatment is to get as close to your due date as possible.

You and your doctor will need to monitor your pregnancy closely and come up with a birth plan. You may require different treatments, depending on certain factors like:

  • Your health.
  • Your baby’s health.
  • Your baby’s gestational age.
  • The amount of bleeding you experience.
Pregnant women sitting near sunlit window

If you have little to no bleeding

Bed rest and pelvic rest. If you have little to no bleeding, your doctor may recommend you stay home for bed rest and pelvic rest. Bed rest means limiting your physical activity during pregnancy and mostly staying in bed. Pelvic rest means avoiding inserting things into your vagina to prevent any bleeding or complications. If you have bleeding, contact your provider immediately and go to the hospital.

Hospital stay. In some cases, your doctor may suggest that you stay at the hospital for close monitoring even if you have little to no bleeding. This allows your healthcare team to act quickly in case of any bleeding.

Cesarean section. If you and your baby are doing well, you will want to plan for a possible C-section around 37 weeks of pregnancy. Even if the placenta is not totally covering the cervical opening, it will tear and cause severe bleeding during vaginal delivery. Discuss options with your doctor to come up with a birth plan that works for you. If your health deteriorates or there are any signs of fetal distress, you may need to have a C-section before your baby reaches term.

If you have heavy bleeding

If you experience heavy or continuous bleeding during pregnancy, you should immediately go to an emergency room. You may need a blood transfusion and emergency C-section. If your baby is preterm, your doctor may give you corticosteroids. These medications will speed up the development of your baby’s lungs and organs and reduce the risk of severe preterm delivery complications.

Placenta previa "do's and don'ts"

There are some basic placenta previa do’s and don’ts that you can keep in mind if you have a placenta previa:

  • Don’t do any strenuous activities, like exercising or lifting heavy objects. This can cause bleeding
  • Avoid sex and don’t insert anything (like a douche) into your vagina. Doing this can cause bleeding.
  • Do continue to eat a healthy diet and get plenty of nutrients.
  • Do talk to your partner, healthcare team and family/friends about your needs and concerns. This can be an extremely stressful time and treatments like bed rest can leave you feeling restless or isolated.
  • Do call your doctor and seek medical attention immediately if you experience any vaginal bleeding.

Placenta previa: some frequently asked questions (FAQs)

Is placenta previa dangerous?

In most cases, a placenta previa will resolve itself. If a placenta previa is detected early in the pregnancy (before 20 weeks), it will likely resolve on its own. This is because as the uterus grows, the placenta will also move upwards. However, if it persists later on into the pregnancy, then it can be dangerous. This is because the delicate blood vessels connecting the placenta and uterus can tear and lead to severe bleeding leading up to or during labor. Severe bleeding at any point during the pregnancy or delivery can be dangerous to both you and your baby. You may need an emergency C-section before your baby is full term. Preterm birth increases your baby’s risk for complications, like breathing problems

Determining blood type. Another point of concern is blood type. If you have Rh-negative blood (A-, B-, AB-, or O- blood types) and your baby is Rh-positive, you will need an immunoglobulin shot to prevent complications. Without this shot, your body will develop anti-Rh antibodies, which will go to attack your baby. The shot prevents the formation of these antibodies.

What are some possible complications of placenta previa?

Complications of placenta previa can include:

  • Restricted fetal growth. If the placenta is in the lower part of the uterus, it may impact the baby’s ability to grow like normal. This will have to be monitored by you and your doctor.
  • Heavy bleeding (hemorrhage). A placenta previa in the later stages of pregnancy can cause serious bleeding even before labor if the blood vessels connecting the uterus and placenta start to tear. Additionally, a placenta previa – regardless of type – can cause serious bleeding when you go into labor. When labor begins, the cervix starts to thin (efface) and open up (dilate) to prepare for delivery. But this can tear the blood vessels connecting the placenta and uterus, causing life-threatening bleeding and endangering both you and your baby.
  • Placental abruption. A placental abruption is when the placenta separates from the uterus before the baby is born. Placenta previa increases the risk of blood vessel tears and therefore increases the risk of the placenta separating from the uterine lining altogether. This cuts your baby off from oxygen and nutrients, can cause heavy bleeding and requires immediate medical attention.
  • Preterm birth. If you are experiencing severe bleeding, you may need an emergency cesarean section (or c-section delivery) before your baby has reached full term. Preterm births increase your baby’s risk for complications like breathing problems and low birth weight.
  • Placenta accreta occurs when the placenta grows too deeply into the uterine wall and doesn’t separate easily during birth. It can lead to massive blood loss and require multiple blood transfusions during birth. If you have placenta previa, you are more likely to have placenta accreta as well.
What is the outlook for women with placenta previa?

There is no way to prevent a placenta previa, but most cases resolve on their own.

Those that do not may cause serious medical complications, like severe bleeding and preterm birth.

Placenta previa is often diagnosed during the second-trimester ultrasound, allowing you and your doctor plenty of time to come up with a plan that meets you and your baby’s needs. That’s why it is so important to receive prenatal care from an expert care team. We are here to help you through every part of your pregnancy and beyond.

References

MedlinePlus: National Library of Medicine. Placenta previa (https://medlineplus.gov/ency/article/000900.htm)

National Library of Medicine. Placenta Previa (https://www.ncbi.nlm.nih.gov/books/NBK539818/)