Placenta Previa

Placenta previa is a condition where the placenta blocks all or part of your cervix late in pregnancy. It happens in about 1 in 200 pregnancies. Pregnancy care providers usually diagnose it in the second trimester during an ultrasound.

Early in pregnancy, it’s normal for the placenta to sit low in your uterus. As your uterus grows, the placenta usually moves up higher. Placenta previa happens when the placenta stays low and blocks your cervix. This can prevent your baby from being born through your vagina.

Placenta previa can cause vaginal bleeding during pregnancy and labor. It also increases your chance of needing a C-section delivery.

Types of placenta previa

The type depends on how much of the placenta covers your cervix:

• Marginal placenta previa: The placenta touches your cervix but doesn’t cover it. It will often move up on its own before your due date.
• Partial placenta previa: The placenta partially covers your cervix. It may move before your due date.
• Complete or total placenta previa: The placenta completely covers your cervix and blocks your baby from coming out of your vagina. It’s less likely to move on its own before your due date.

Symptoms of placenta previa

The most common symptom is bright red vaginal bleeding (usually in the third trimester). The bleeding may start, stop and then start again over several days. The amount can also vary. It often doesn’t cause pain, but it can cause mild cramping.

This usually happens because your body is preparing for labor. In the third trimester, your cervix begins to thin and stretch. If the placenta is touching or covering your cervix, this can cause bleeding.

Placenta previa causes

Healthcare providers don’t know the exact cause. There are some factors that can increase your risk of placenta previa, including your medical history and certain lifestyle habits.

Risk factors

These factors increase your risk for placenta previa:

• You smoke cigarettes or use cocaine
• You’re 35 or older
• You’ve been pregnant several times before
• You’re pregnant with twins, triplets or more
• You’ve had surgery on your uterus, including a C-section or a D&C
• You have a history of uterine fibroids

Complications of this condition

If you have placenta previa, there are risks for both you and your baby.

Complications from placenta previa for you include:

• Bleeding: Severe bleeding can happen during pregnancy, labor or delivery.
• Early birth: Your healthcare provider may need to deliver early with a C-section before your baby is full term (40 weeks).
• Blood loss: Losing too much blood can cause low blood pressure, pale skin or shortness of breath.
• Placenta accreta: The placenta grows too deeply in the wall of your uterus. This can cause severe bleeding after delivery.
• Placental abruption: The placenta separates from your uterus before your baby is born. This decreases your baby’s supply of oxygen and nutrients.

Complications for your baby include:

• Preterm birth: Being born preterm comes with risks, like breathing problems or trouble feeding.
• Low birth weight: Smaller babies may have trouble getting warm and gaining weight.

How doctors diagnose placenta previa

Pregnancy care providers usually find placenta previa during an ultrasound around 20 weeks of pregnancy. They may also diagnose it if you have symptoms like vaginal bleeding.

If your provider finds placenta previa, they’ll check the placenta’s position with more ultrasounds for the rest of your pregnancy.

How is placenta previa treated?

Treatment of placenta previa depends on:

• How severely you’re bleeding
• The gestational age of your baby
• The position of the placenta and your baby
• The health of you and your baby

The goal is to get you as close to your due date as possible. Having a C-section delivery is often the safest treatment when you have placenta previa.

If you have little or no bleeding, your provider may take a watch-and-wait approach. If they find placenta previa in the second trimester, it may go away on its own. The placenta can move until about 32 to 34 weeks. Your provider will monitor you closely and watch for bleeding.

They may recommend:

• Avoiding strenuous activities, like running, lifting, jumping and exercising
• Avoiding sex or putting anything in your vagina
• More frequent prenatal appointments and ultrasounds
• Getting extra rest

For moderate to severe cases of placenta previa or frequent bleeding, treatment could include:

• Staying in the hospital for closer monitoring
• Medicine to prevent early labor
• Steroid shots to help your baby’s lungs develop
• Blood transfusions for heavy bleeding
• An emergency C-section for uncontrolled bleeding

How likely is it for placenta previa to go away?

Placenta previa often goes away on its own if your provider finds it in the second trimester. This is because the placenta typically moves up as your uterus grows. But the later it is in pregnancy, the less likely it is to move. Your provider will monitor the placenta to see if it moves before delivery.

When should I see my healthcare provider?

Call your healthcare provider immediately if you’re bleeding, cramping or having pelvic pain during your pregnancy, especially in the second half. Seek emergency care in an ER if you’re bleeding severely.

What can I expect if I have placenta previa?

It depends on your symptoms and how far along you are. Most people can expect:

• Frequent monitoring to check the position of the placenta and watch for bleeding
• Changes to your daily activities, like limiting exercise and avoiding sex
• Extra care after delivery, including blood tests to check your blood levels

Tell your healthcare provider about your typical activities. They’ll recommend changes you should make for safety.

If you’ve had placenta previa in a past pregnancy, your chances of having it again are slightly higher. If you’re pregnant, be sure to tell your healthcare provider.

Can I still have a vaginal delivery with placenta previa?

It’s possible. But a C-section is usually the safest option. If the placenta covers even a tiny part of your cervix, a vaginal delivery can cause severe bleeding.

Will my baby be born early if I have placenta previa?

Maybe. Your healthcare provider will look at how much you’re bleeding, the position of the placenta and the baby’s gestational age before deciding if an early delivery is necessary. Sometimes, an early delivery at 36 weeks is the safest option for both you and your baby.

Can babies survive placenta previa?

Most people still have healthy deliveries. Your pregnancy care provider will monitor you closely so both you and your baby are safe.