Placenta Previa: Causes, Symptoms & Treatment

Placenta previa is a pregnancy condition where the placenta lies low in the uterus and partly or completely covers the cervix — the opening through which the baby would be born. It is one of the more common causes of bleeding in the second half of pregnancy, and understandably it worries many expecting mothers. As an obstetrician caring for pregnancies across Chennai, I want to reassure you: with regular monitoring and a planned approach to delivery, the great majority of women with placenta previa have safe outcomes for both mother and baby.

What Is Placenta Previa?

The placenta is the organ that develops inside the uterus during pregnancy to supply your baby with oxygen and nutrients. Normally it attaches to the upper or side wall of the uterus, well away from the cervix. In placenta previa, the placenta implants low down and overlaps or covers the cervical opening. Because the lower part of the uterus stretches and thins as pregnancy advances, a placenta in this position can bleed — typically painlessly and without warning. The condition is usually picked up on a routine pregnancy scan rather than from symptoms, which is one more reason regular antenatal care matters so much.

Types and Grades of Placenta Previa

Placenta previa is described by how much of the cervix the placenta covers. Understanding the grade helps explain the level of monitoring and the likely mode of delivery.

• Low-lying placenta: The placenta is near the cervix but does not cover it. Many of these move up as pregnancy progresses.

• Marginal previa: The edge of the placenta reaches the border of the cervix but does not cover the opening.

• Partial previa: The placenta partially covers the cervical opening.

• Complete (major) previa: The placenta completely covers the cervix. This is the most significant grade and almost always requires a planned caesarean delivery.

What Causes Placenta Previa?

There is not always a single cause, but several factors are known to increase the likelihood of the placenta implanting low in the uterus:

• Previous caesarean section or uterine surgery: Scarring from earlier surgery can affect where the placenta implants.

• Previous placenta previa: Having had it in an earlier pregnancy raises the chance of recurrence.

• Multiple previous pregnancies: The risk rises with the number of pregnancies a woman has had.

• Carrying twins or multiples: A larger placenta is more likely to extend low.

• Advanced maternal age: Risk increases for mothers over 35.

• Smoking: Smoking during pregnancy is associated with a higher risk.

Symptoms and Warning Signs

The classic sign of placenta previa is sudden, painless, bright-red vaginal bleeding in the second half of pregnancy. The bleeding may be light or heavy, and it can stop and then return. Unlike the cramping of labour, it is usually not painful. Any vaginal bleeding in pregnancy should be treated as urgent — if it happens, contact your doctor or go to your delivery hospital straight away rather than waiting to see if it settles. Even a small amount of bleeding needs to be checked, because placenta previa bleeding can become heavy quickly.

How Placenta Previa Is Diagnosed

Most placenta previa is found at the routine anomaly scan around 18-22 weeks, often before any bleeding occurs. If the placenta is low at that stage, a follow-up scan — usually a transvaginal ultrasound, which is safe in this situation — is arranged in the third trimester to see whether it has moved up. If you bleed at any point, an ultrasound is done to check the placental position. Because the diagnosis relies on imaging, pregnancy ultrasound scans are central to both detecting and tracking placenta previa.

Treatment of Placenta Previa

There is no treatment that physically moves the placenta, so management instead focuses on keeping mother and baby safe until the right time for a controlled delivery. The exact plan depends on the grade of previa, how many weeks pregnant you are, and whether there is any bleeding. This is general information; your own management is always tailored by your obstetrician to your specific situation.

• Expectant management (no bleeding): If there is no bleeding, the pregnancy is monitored with scheduled scans, pelvic rest, and clear instructions on what to do if bleeding starts. The aim is to safely reach a gestation where the baby is mature.

• Hospital monitoring (with bleeding): Bleeding episodes usually mean admission to hospital for observation, sometimes with steroid injections to help the baby's lungs mature in case early delivery becomes necessary.

• Managing blood loss: Iron supplementation or, if bleeding is significant, blood transfusion may be needed to keep the mother well.

• Planned delivery: For persistent previa, a planned caesarean section is scheduled — generally before labour begins — to avoid the risk of heavy bleeding. The timing balances the baby's maturity against the risk of an unplanned bleed.

This kind of close, structured monitoring is part of high-risk pregnancy care, where a known complication is watched carefully and a delivery plan is made well in advance.

Placenta Previa Self-Care: What You Can Do at Home

Alongside your medical care, a few practical steps help reduce the risk of bleeding and keep you prepared:

• Pelvic rest: Avoid intercourse, tampons, and anything inserted vaginally as advised by your doctor.

• Avoid strenuous activity: No heavy lifting, vigorous exercise, or activities that strain the abdomen.

• Rest more, stand less: Take it easy and listen to your body, especially in the third trimester.

• Know your emergency plan: Keep your hospital bag ready, stay within easy reach of your delivery hospital as you near term, and know exactly how you will get there if bleeding starts.

• Never ignore bleeding: Any vaginal bleeding means contacting your doctor or going to hospital immediately.

Delivery with Placenta Previa

For complete or major placenta previa, a planned caesarean section is the safe route of delivery, because the placenta blocks the baby's path and a vaginal birth would risk severe bleeding. For a minor low-lying placenta that has moved sufficiently away from the cervix by the third trimester, a vaginal delivery may still be possible. If you would like to understand the difference between the two routes of birth, our guide on normal delivery versus C-section explains what to expect from each.

When to Seek Help

Contact your doctor or go to your delivery hospital straight away if you have any vaginal bleeding, abdominal pain, or contractions during pregnancy — and especially if you have a known placenta previa. Early action keeps both you and your baby safe. If you have been told you have a low-lying placenta or placenta previa and would like experienced, reassuring care with a clear delivery plan, book a consultation with Dr. Rukkayal Fathima.