If a scan report mentions a "low-lying placenta" or "placenta previa," it can sound alarming. In most cases, though, it resolves on its own. Here's what these terms mean.
Where the Placenta Normally Sits
The placenta is the organ that nourishes your baby, attaching to the wall of the uterus. It can implant anywhere on that wall — top, front, back, or side. Usually it sits well away from the cervix (the opening at the bottom of the uterus).
What "Low-Lying Placenta" Means
A low-lying placenta is one that has implanted low in the uterus, close to the cervix. This is often noticed at the 20-week anomaly scan.
Here's the reassuring part: as pregnancy progresses and the uterus grows upward, the placenta usually appears to "migrate" away from the cervix. In the large majority of cases, a placenta that's low at 20 weeks has moved to a safe position by the third trimester.
What "Placenta Previa" Means
Placenta previa is when the placenta partially or completely covers the cervix. Because the cervix is the baby's exit route, a placenta covering it can cause bleeding and means a vaginal birth isn't safe — a caesarean is planned instead.
Previa is diagnosed later in pregnancy, once there's been time for the placenta's position to settle. Only a small proportion of early low-lying placentas remain as true previa.
How It's Monitored
If your 20-week scan shows a low-lying placenta, you'll typically be offered a follow-up scan (often around 32–36 weeks) to check its final position. This extra scan is a routine precaution.
Signs to Report
If you have a low placenta, your care team may advise you to report any vaginal bleeding promptly. Always follow their specific guidance.
The Key Message
A low-lying placenta at 20 weeks is common and usually resolves. True placenta previa is less common and is carefully managed to keep you and your baby safe.
This article is for general information only and is not a substitute for professional medical advice.
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Mascot Healthcare Clinic, Akoka (Yaba), Lagos offers ultrasound scans by appointment only, Monday–Saturday, 9am–5pm. Book online and choose a time that works for you.