What Is Placenta Previa?
Placenta previa is when a pregnant person's placenta blocks the opening to the cervix that allows the baby to be born. It can cause severe bleeding during pregnancy and delivery. Mothers with placenta previa are also at a higher risk of delivering prematurely before 37 weeks of pregnancy.
The placenta is an organ that grows inside the lining of your uterus during pregnancy. It connects to the umbilical cord and carries oxygen and nutrients from you to your unborn child. It also moves waste away from your baby.
Placenta previa happens when the placenta partly or completely covers the cervix, which is the opening of the uterus. Your baby passes into the cervix and through the birth canal during a vaginal delivery. Normally, the placenta does not attach near the cervix.
Here's what happens with placenta previa: As your cervix opens during labor, it can cause blood vessels that connect the placenta to the uterus to tear. This can lead to bleeding and put both you and your baby at risk. People who have this condition need to have a cesarean section (C-section) to keep this from happening.
Types of Placenta Previa
You may have different outcomes, depending on the type of placenta previa you have. Types include:
Complete previa
Complete previa is when the placenta covers the entire opening of the cervix.
Partial previa
Partial previa is when the placenta covers part of the opening of the cervix.
Marginal previa
Marginal previa, also called low-lying placenta, is when the placenta is close to the opening of the cervix but doesn't cover it. In 90% of cases, marginal previa gets better on its own before the baby is due.
Placenta Previa Symptoms
You might notice:
- Bright red bleeding from the vagina during the second half of your pregnancy. It can range from light to heavy, and it's often painless.
- Contractions along with the bleeding. You might feel the cramping or tightening that comes with contractions, or feel pressure in your back.
If you bleed too much, you may have other symptoms, such as anemia, pale skin, a rapid and weak pulse, shortness of breath, or low blood pressure.
Placenta Previa Risk Factors
You may be more likely to have placenta previa during your pregnancy if you:
- Smoke
- Use cocaine
- Have had several pregnancies before
- Are older than 35
- Have had surgeries on your uterus, including a C-section
- Are pregnant with twins or triplets
Can placenta previa cause a miscarriage?
A miscarriage happens when a pregnancy ends before 20 weeks. It’s unlikely that placenta previa would cause a miscarriage because doctors usually diagnose it around or after the 20th week of pregnancy.
Can placenta previa cause a preterm birth?
A preterm birth is likely to happen as a complication of placenta previa if you don’t get an early diagnosis or if it’s not treated or monitored well. Placenta previa is responsible for 5% of all preterm deliveries. Your doctor may recommend an emergency C-section for preterm delivery when you have heavy, life-threatening bleeding.
Having placenta previa complications can also make the risk of health problems and death for the baby 3 to 4 times higher.
Placenta Previa Diagnosis
Doctors often diagnose placenta previa during an ultrasound on one of your routine prenatal visits. The test uses sound waves to show if your placenta covers the opening from your uterus to your cervix. They'll start with a device called a transducer placed on your belly. But if they need a better look, they'll use a transducer that goes inside your vagina.
Placenta Previa Treatment
There's no cure for placenta previa. The goal of treatment is to limit the bleeding so you can get as close as possible to your due date.
Your doctor could give you medicine to prevent premature labor. They may also give you corticosteroid shots to help your baby’s lungs develop faster. Once they feel that the baby can be safely delivered (by about 36 weeks of pregnancy), they’ll schedule a C-section. If your bleeding won’t stop, you’ll need an emergency C-section, even if your baby is not full term.
Treatment depends on:
- The amount of bleeding. If it's light, your doctor might suggest you avoid activities including sex and exercise. If it's heavy, you may need to go to the emergency room, stay in the hospital, and get a blood transfusion.
- How close you are to your due date
- Your health and your baby's health
- The position of the placenta and the baby
When to Contact Your Doctor
Check with your doctor if you have bleeding during your second or third trimester. If it's severe, go to the hospital.
Takeaways
Placenta previa is a condition where the placenta is close to or covers the opening of the cervix. You likely won't show any symptoms when you have it. Doctors often find it during a routine second-trimester ultrasound. But when you have symptoms, it involves sudden but painless bleeding from the vagina. You may also feel contractions or tightening in your belly. See a doctor right away if you have these symptoms or others during pregnancy.
Placenta Previa FAQs
What is the biggest risk with placenta previa?
The biggest risk with placenta previa is severe and life-threatening bleeding. If the bleeding doesn’t stop, you may have to have a preterm delivery.
What is the best treatment for placenta previa?
The best treatment for placenta previa is delivery of the baby after 36 weeks.
What causes placenta previa in pregnancy?
Doctors don’t know what causes placenta previa. But you’re likely to have it if you have risk factors like being 35 or older, if you’ve been pregnant before or have had C-sections, if you’ve had fertility treatments, or if you smoke cigarettes or use cocaine.
