Placenta Previa
Content reviewed against published ACOG, March of Dimes, Mayo Clinic guidelines
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If your baby has been diagnosed with or you suspect placenta previa, here is what the evidence says.
The short answer
Placenta previa means the placenta partially or completely covers the cervix. It is found in about 1 in 200 pregnancies at delivery. Many cases of low-lying placenta detected on mid-pregnancy ultrasound resolve on their own as the uterus grows. When placenta previa persists, a planned cesarean delivery is necessary, and with proper monitoring most outcomes are excellent.
Key takeaways
- Placenta previa means the placenta partially or completely covers the cervix. It is found in about 1 in 200 pregnancies at delivery. Many cases of low-lying placenta detected on mid-pregnancy ultrasound resolve on their own as the uterus grows. When placenta previa persists, a planned cesarean delivery is necessary, and with proper monitoring most outcomes are excellent.
- Usually normal when: A low-lying placenta was noted on an early ultrasound and your provider says it will likely resolve
- Call your doctor if: You have bright red painless vaginal bleeding that is heavy (soaking a pad in an hour) or does not stop
- Varies by age — see the age-by-age breakdown below
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By Age
What to expect by age
First trimester
A low-lying placenta noted on first trimester ultrasound is very common and almost always resolves. As the uterus expands, the placenta appears to "migrate" upward away from the cervix. Providers generally reassure patients that this early finding is not concerning and will be re-evaluated later in pregnancy.
Second trimester
Placenta previa may be identified during the anatomy scan around 18-22 weeks. At this stage, about 90% of low-lying placentas will still move away from the cervix by the third trimester. A follow-up ultrasound is typically scheduled around 28-32 weeks to reassess the position. You may be advised to avoid intercourse and strenuous activity if placenta previa is diagnosed.
Third trimester
If placenta previa persists into the third trimester, your provider will monitor you closely for bleeding. You may be placed on pelvic rest (no intercourse, tampons, or vaginal exams). Painless bright red vaginal bleeding is the hallmark symptom. If you have significant bleeding or the placenta fully covers the cervix, a cesarean delivery is planned, typically around 36-37 weeks.
Postpartum
After delivery by cesarean for placenta previa, recovery is similar to any cesarean birth. In some cases, the placenta may have grown into the uterine wall (placenta accreta), which your provider will have screened for in advance. Postpartum hemorrhage risk is slightly higher, so your care team will monitor you closely after delivery.
What Should You Do?
When to take action
- A low-lying placenta was noted on an early ultrasound and your provider says it will likely resolve
- A follow-up ultrasound shows the placenta has moved away from the cervix
- You have no vaginal bleeding and your baby is growing normally
- Your provider is monitoring the situation and has not expressed immediate concern
- You have been diagnosed with placenta previa and experience any amount of vaginal spotting or bleeding
- You feel contractions or cramping before your scheduled delivery date
- You are unsure about activity restrictions or your delivery plan
- You have bright red painless vaginal bleeding that is heavy (soaking a pad in an hour) or does not stop
- You experience heavy bleeding with contractions, dizziness, or signs of shock (rapid heartbeat, feeling faint)
Doctor Visit Checklist
Bring this checklist to your next pediatrician visit to discuss Placenta Previa.
Things to mention
- You have been diagnosed with placenta previa and experience any amount of vaginal spotting or bleeding
- You feel contractions or cramping before your scheduled delivery date
- You are unsure about activity restrictions or your delivery plan
Observations to share
- You have been diagnosed with placenta previa and experience any amount of vaginal spotting or bleeding
- You feel contractions or cramping before your scheduled delivery date
- You are unsure about activity restrictions or your delivery plan
Urgent signs to report immediately
- You have bright red painless vaginal bleeding that is heavy (soaking a pad in an hour) or does not stop
- You experience heavy bleeding with contractions, dizziness, or signs of shock (rapid heartbeat, feeling faint)
My notes
From ismybabyalright.com — free, evidence-based baby health guides
Related Resources
Frequently asked questions
Is placenta previa normal?
When should I call the doctor about placenta previa?
When is placenta previa normal?
What causes placenta previa?
What should I mention to my pediatrician about placenta previa?
Is placenta previa normal at First trimester?
Is placenta previa normal at Second trimester?
Should I go to the ER for placenta previa?
Does placenta previa go away on its own?
References
- [1]American College of Obstetricians and Gynecologists. Placenta Previa. ACOG FAQ, 2021. ACOG
- [2]March of Dimes. Placenta previa. March of Dimes, 2023. March of Dimes
- [3]Mayo Clinic. Placenta previa - Symptoms and causes. Mayo Clinic, 2023. Mayo Clinic
All content follows our editorial policy and is reviewed against published clinical guidelines.
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Bottom line
Most cases of placenta previa are normal. Talk to your pediatrician if you have bright red painless vaginal bleeding that is heavy (soaking a pad in an hour) or does not stop.
Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.
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