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Placenta Previa

A Quick Guide

Warning: If you experience bleeding during pregnancy, contact your midwife or doctor immediately. If the bleeding or pain is severe, call triple zero (000) and ask for an ambulance.

Bleeding during pregnancy can be a sign of a placental complication known as placenta praevia. This condition occurs when the placenta implants low in the uterus and may partially or completely block the cervix. In this guide, we cover the definition of placenta praevia, common symptoms, and how it is managed.

What is placenta praevia?

Placenta praevia occurs when the placenta attaches close to or completely covers the cervix, making vaginal birth difficult or impossible. It is sometimes referred to as a low-lying placenta. It affects approximately 0.3-0.5% of pregnancies in Australia.

Placenta praevia is usually identified before labour begins through routine prenatal care and ultrasound scans.

Placenta praevia is typically diagnosed during the standard 18-20 week morphology ultrasound scan.

While it is often detected at 20 weeks, in approximately 90% of cases the placenta moves upwards and away from the cervix as the uterus grows, resolving on its own by the third trimester.

If a low-lying placenta is found during the 20-week scan, follow-up scans are usually scheduled at around 32-34 weeks to recheck its position.

Signs and symptoms of placenta praevia

Signs can include vaginal bleeding after 28 weeks of pregnancy. Typical signs of placenta praevia include painless vaginal bleeding during the second or third trimester.

Many people with minor placenta praevia may not experience symptoms until labour begins, whereas major placenta praevia can cause heavier bleeding and complications during delivery.

If placenta praevia is confirmed near term, a planned Caesarean section is usually recommended to help protect the safety of both mother and baby.

This information has been reviewed by Neonatologist, Dr John Smyth MBChB, FRACP FRCPCH.

See FAQs Below

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FAQs

Is placenta previa dangerous for the baby?

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Placenta praevia can pose risks to the baby, primarily due to preterm birth and restricted foetal growth. According to studies, women with placenta praevia have a higher likelihood of preterm birth, with many delivering before 37 weeks. Additionally, placenta praevia is associated with higher levels of maternal and foetal morbidity, requiring careful monitoring and management.

 

How is placenta previa diagnosed?

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Placenta praevia is typically diagnosed through ultrasound imaging, either during routine scans or after symptoms such as painless vaginal bleeding appear in the second or third trimester. Scans also help determine the classification of placenta praevia, which refers to how much of the cervix is covered.

What are the treatment options for placenta previa?

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For treatment options consult with a medical professional as management depends on the severity of the condition. If bleeding is mild, doctors may recommend modified activity and close monitoring. In cases of severe bleeding, hospitalisation and early caesarean delivery may be necessary.

Can I have a vaginal birth with placenta previa?

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In most cases, vaginal birth is not possible if the placenta completely covers the cervix. A caesarean section is usually required to ensure a safe delivery. However, if the placenta is low-lying but does not fully cover the cervix, vaginal birth may still be an option with careful monitoring.

 

The vital role of research

Whilst relatively rare, research indicates that cases of placenta praevia are increasing alongside rising caesarean rates. Charities such as Running for Premature Babies play a vital role in funding essential medical research focused on prenatal and postnatal care.

Continued advancements in screening tools and ongoing research could significantly improve outcomes for mothers affected by placenta praevia, giving babies a better chance of survival.

At Running for Premature Babies, we are incredibly grateful for our dedicated community of fundraisers and volunteers.

If you’d like to support research into preterm birth or complications such as placenta praevia, including studies into the classification of placenta praevia, your donation can make a lasting impact. Help equip hospitals with essential NICU resources by donating here.

Disclaimer: This information by Running for Premature Babies Foundation is educational and informative in nature and is not medical advice or a healthcare recommendation. For further information, please seek professional medical advice from a qualified healthcare provider.

References

Healthdirect Australia. (n.d.). Pregnancy, Birth and Baby: Placenta praevia.
https://www.pregnancybirthbaby.org.au/placenta-praevia
Retrieved 15th May 2025
Australian Institute of Health and Welfare. (2012). Maternal morbidity data in Australia: An assessment of the feasibility of standardised collection. AIHW.
https://www.aihw.gov.au
Retrieved 15th May 2025
Zhang, L., Bi, S., Du, L., et al. (2020). Effect of previous placenta previa on outcome of next pregnancy: A 10-year retrospective cohort study. BMC Pregnancy and Childbirth, 20, 212.
https://doi.org/10.1186/s12884-020-02890-3
Retrieved 15th May 2025
Royal College of Obstetricians and Gynaecologists. (n.d.). Placenta praevia, placenta accreta and vasa praevia.
https://www.rcog.org.uk/for-the-public/browse-our-patient-information/placenta-praevia-placenta-accreta-and-vasa-praevia/
Retrieved 9th April 2026
BMJ Best Practice. (2025). Placenta praevia.
https://bestpractice.bmj.com/topics/en-gb/667
Retrieved 26th May 2025