What is Placenta Previa?

2 min read March 25, 2025Week 27

Key takeaways

2 min

Understand that placenta previa affects only 1 in 200-250 pregnancies and involves the placenta forming in the lower uterus around 12-13 weeks.
Know that routine ultrasounds check where the placenta is; if it's low, you'll have another scan at around 32 weeks to confirm whether it's placenta previa.
Know that women over 30-35, those with previous C-sections, IVF, or urogenital infections have higher risk factors for developing placenta previa.
Take comfort that in 95.5% of cases, a low-lying placenta naturally moves upward by 36 weeks of pregnancy without intervention.
Contact the hospital straight away if you have a low-lying placenta and notice any vaginal bleeding, contractions or pain, and discuss monitoring plans with your healthcare provider.

Placenta previa occurs when the placenta forms in the lower half of the uterus around 12-13 weeks of pregnancy, affecting 1 in 200-250 pregnancies. Most cases resolve naturally, with 95.5% of low-lying placentas moving upward by 36 weeks, allowing for continued healthy pregnancy. With a low-lying placenta, any vaginal bleeding means contacting the hospital straight away.

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What is Placenta Previa?

The placenta begins to form around 12-13 weeks. In some cases, it develops in the lower half of the uterus [1]. This is called a low-lying placenta or placenta previa. According to scientists, women at risk include those who have had IVF, caesarean section, infections of the urogenital tract, as well as those who become pregnant after 30-35 years. However, placenta previa is rather rare and only occurs in one out of 200-250 pregnant women [2].

How can you tell if you have placenta previa?

The doctor can see a low-lying placenta on ultrasound screening in the first and early second trimester of pregnancy [3], but placenta previa is only confirmed on a follow-up scan, usually at around 32 weeks. If you have been told you have a low-lying placenta, try not to worry. In most cases, the low-lying placenta rises. In 89.9% of cases, this occurs by 32 weeks, and in 95.5% of cases, it occurs by 36 weeks [4]. If you have any vaginal bleeding, contractions or pain, contact the hospital straight away.

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Frequently asked questions

Placenta previa occurs when the placenta develops in the lower half of the uterus around 12-13 weeks of pregnancy. While it affects only 1 in 200-250 pregnancies, it can be managed effectively to maintain a healthy pregnancy with proper medical monitoring.

A routine ultrasound in the first or early second trimester can show a low-lying placenta, but placenta previa is only confirmed on a follow-up scan, usually at around 32 weeks, because the placenta often moves up as the uterus grows.

Yes, in most cases placenta previa resolves naturally as the pregnancy progresses. Studies show that 89.9% of low-lying placentas move upward by 32 weeks, and 95.5% resolve by 36 weeks of pregnancy.

Women over 30-35 years old, those who have had IVF treatments, previous cesarean sections, or infections of the urogenital tract are at higher risk. However, placenta previa can occur in any pregnancy regardless of risk factors.

While concerning, placenta previa shouldn't cause excessive worry as it's highly treatable and often resolves naturally. With proper medical monitoring and care, most women with this condition can still have a healthy pregnancy and delivery. If you have a low-lying placenta, contact the hospital straight away if you have any vaginal bleeding, contractions or pain.

Medical Disclaimer

This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or qualified health provider with any questions you may have regarding a medical condition.

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Medically reviewed content

Reviewed by healthcare professionals · Updated October 2, 2026

This article is based on peer-reviewed research and trusted medical sources.

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