Placenta previa is when the placenta grows low in the uterus and covers all or part of the opening to the cervix. This can block the path your baby needs to take during a vaginal birth, which is why it changes how your delivery is planned. It happens in about 1 out of 200 pregnancies.
Seek care right away if you have any vaginal bleeding during pregnancy. With placenta previa, bleeding is often sudden, bright red, and painless. It can start near the end of the second trimester or in the third trimester. Bleeding may be light and stop on its own, but it can also be heavy and return days or weeks later. Call your provider or go to the emergency room for any bleeding, and call 911 if bleeding is heavy or you feel dizzy, faint, or short of breath.
The Three Types of Placenta Previa
How much of the cervix the placenta covers determines the type. This matters because it affects whether the placenta is likely to move out of the way as the pregnancy continues.
- Marginal: The placenta sits next to the cervix but does not cover the opening.
- Partial: The placenta covers part of the cervical opening.
- Complete: The placenta covers the entire cervical opening.
Who Is More Likely to Have Placenta Previa
Doctors don’t fully know why placenta previa happens, but it’s more common in people who have:
- An abnormally shaped uterus
- Had many pregnancies in the past
- A multiple pregnancy, such as twins or triplets
- Scarring in the uterus from past surgery, a C-section, or an abortion
- Had in vitro fertilization (IVF)
- Had placenta previa in a previous pregnancy
Smoking, cocaine use, and having children at an older age may also raise the risk.
How Placenta Previa Is Diagnosed and Monitored
Your provider diagnoses placenta previa with a pregnancy ultrasound. It’s common for the placenta to sit low early in pregnancy. As the uterus stretches and grows, the placenta usually moves up and away from the cervix on its own. Some placenta previas resolve this way by around 32 to 35 weeks, which allows for a normal labor. Others don’t resolve, which is why follow-up ultrasounds are used to track the placenta’s position as the pregnancy progresses.
Activity Restrictions: What Your Provider May Recommend
If your placenta is near or covering the cervix, your provider may suggest changes to reduce the chance of bleeding. These recommendations vary from person to person, so ask your own provider which ones apply to you.
- Reducing certain activities
- Bed rest, in some cases
- Pelvic rest — this generally means no sex, no tampons, and no douching, and nothing else placed in the vagina
If you have bleeding, you may need to stay in the hospital so your care team can monitor you and your baby closely. Depending on your situation, your provider might also discuss blood transfusions, medicine to help delay early labor, a Rhogam shot if your blood type is Rh-negative, or steroid shots to help your baby’s lungs mature. Whether any of these apply to you is a decision for your care team, not something to plan on your own.
Practical next steps for Placenta Previa
- Confirm the type and position. Your provider tracks whether the placenta is marginal, partial, or complete, and whether it’s moving away from the cervix over time.
- Watch for bleeding. Any bleeding gets reported right away, since it can change the monitoring plan.
- Reassess in the third trimester. Follow-up ultrasounds show whether the previa has resolved as the due date approaches.
- Plan the birth. If the placenta still covers the cervix, a cesarean birth is planned, since a vaginal delivery could cause severe bleeding. Your provider weighs the risk of bleeding against early delivery, and after 36 weeks, delivery may be the safest option.
- Prepare for the unexpected. An emergency cesarean can happen if bleeding becomes heavy and can’t be controlled, even before the planned delivery date.
Placenta Previa vs. Placenta Accreta
These two conditions are related but not the same. Placenta previa is about location — the placenta covers the cervix. Placenta accreta is about attachment — part or all of the placenta grows too deeply into the uterine wall and doesn’t separate normally. Placenta accreta can cause severe blood loss during delivery and is usually found during pregnancy with routine ultrasound. If you’ve had placenta previa along with a prior cesarean birth, ask your provider whether they are also screening for placenta accreta, since having both raises different concerns.
Where current knowledge about Placenta Previa stops
If you’ve had a previous cesarean birth, other uterine surgery, a prior placenta previa, or you’re carrying twins or triplets, your case may need closer monitoring, since these factors are linked to higher risk. This page is a general overview and doesn’t cover every personal scenario, insurance question, or hospital’s specific protocol. How often you’re monitored, which restrictions apply to you, and your exact delivery date are decisions your own obstetric team makes based on your ultrasounds, your bleeding history, and your overall health.
Questions readers ask about Placenta Previa
Does placenta previa always mean I’ll need a C-section?
Not always. Some cases resolve as the placenta moves away from the cervix as pregnancy continues, allowing for a normal labor. If the placenta still covers the cervix later in pregnancy, a cesarean birth is generally needed because a vaginal delivery could cause severe bleeding.
Can placenta previa go away on its own?
Yes, in some cases. As the uterus grows, the placenta often moves upward and away from the cervix. Some previas resolve by around 32 to 35 weeks. Whether yours will resolve depends on the type and position, which your provider tracks with follow-up ultrasounds.
Do I have to be on bed rest the whole pregnancy?
Not necessarily. Bed rest is one option a provider might recommend if the placenta is near or covering the cervix, but recommendations vary by situation. Some people are advised to reduce activity or follow pelvic rest instead. Ask your provider what’s appropriate for your specific case.
Is placenta previa dangerous?
It can be serious. The main risk is heavy bleeding, which can be life-threatening and may require early delivery. With regular prenatal care, placenta previa is often found on ultrasound before symptoms start, which helps your care team plan ahead and reduce risk.
Related Reading on Reproductive Health Ctr
- Pregnancy & Preconception — what to know about early pregnancy and pregnancy testing.
- Reproductive Health & Preventive Care — how to prepare for prenatal visits and what routine care covers.
- Read our full Medical Disclaimer
Educational Disclaimer
This article is for general educational purposes only. It is not medical advice, diagnosis, or treatment, and reading it does not create a provider-patient relationship. Placenta previa monitoring and delivery decisions depend on your specific ultrasound findings, bleeding history, and overall health, which only your own healthcare provider can evaluate. If you are pregnant and experience vaginal bleeding, contact your provider or seek emergency care right away. If you are having a medical emergency, call 911 or go to the nearest emergency room.