Placenta Previa vs Abruptio Placenta: Differences & More

By Dr. Kenosha Gleaton, OBGYN

Did you know that the body grows more than a fetus during pregnancy? An entirely new organ also develops during gestation. [1] This organ is known as the placenta, and its job is to protect, nourish, and filter various substances for your baby. More specifically, the placenta provides the baby with oxygen and nutrients, produces hormones, removes harmful waste, and more. [1] The placenta attaches to the wall of the uterus and is connected to the baby via the umbilical cord. The placenta is only a temporary organ and is delivered shortly after childbirth. 

Unfortunately, there can be complications with the placenta that may impact pregnancy or childbirth. Two complications we’ll be discussing here are placenta previa and abruptio placenta, also known as placental abruption. A placenta previa is characterized by the placenta covering all or part of the cervix, which blocks the baby’s vaginal exit. [2] Placental abruption, however, is characterized by the placenta partially or completely separating from the wall of the uterus. [3] The main difference between the two is whether or not the placenta is still attached to the uterus. 

What Is Placenta Previa?

Placenta previa is a condition during pregnancy where the placenta blocks all or part of your baby’s exit from your vagina. Placenta previa occurs in about 1 in 200 pregnancies and is usually diagnosed in the second trimester. [2] Those with placenta previa will typically need a C-section delivery to improve delivery outcomes. 

Types of Placenta Previa

There are a few different types of placenta previa which are distinguished as marginal, partial, and complete. Each type of placenta previa can lead to vaginal bleeding during pregnancy and labor. The types differ based on where the placenta is positioned. For example [2]:

• Marginal placenta previa: the placenta is touching but not covering the cervix. 
• Partial placenta previa: the placenta partially covers the cervix. 
• Complete or total placenta previa: the placenta is completely covering the cervix, blocking the vagina. 

Symptoms of Placenta Previa

The most common symptom of placenta previa is bright red vaginal bleeding. Bleeding is usually seen near the second half of pregnancy and can come and go. Bleeding usually isn’t accompanied by any pain, and the amount of bleeding can vary. [2] Some people may experience mild cramping or contractions in the abdomen or back. It’s also possible to not experience any bleeding. There are many different causes for cramping during pregnancy and vaginal bleeding, so you should always speak to a provider if you notice any new or strange symptoms. 

Causes & Risk Factors for Placenta Previa

The placenta is able to stretch and grow through pregnancy and can change position as pregnancy progresses. It’s common for the placenta to be low in the uterus during early pregnancy, but the placenta should move to the top of the uterus when nearing the third trimester. [1-2] When this doesn’t happen and the placenta remains low in the uterus, it can block the cervix and make it difficult for the baby to exit from the vagina, leading to a diagnosis of placenta previa. We aren’t entirely sure why the placenta doesn’t always move to the top of the uterus, however, we have established some factors that can influence someone’s risk of developing placenta previa. These risk factors include [2]:

• Cigarette smoking
• Use of illicit drugs
• Age 35 or older
• History of uterine surgery, including a C-section or D&C (dilation and curettage)
• History of uterine fibroids (learn how to get rid of fibroids here)
• Previous pregnancies
• Pregnant with multiples (twins, triplets, etc)

Diagnosing Placenta Previa

Placenta previa is often easily diagnosed during routine ultrasound appointments. A provider may also suspect placenta previa if someone is experiencing symptoms such as vaginal bleeding or abdominal pain. [2] Placenta previa is sometimes noticed during a 20-week ultrasound, sometimes referred to as an anatomy scan. This scan is typically done to check on the development of fetal organs, body parts, and to detect any disorders or abnormalities. Your provider should also be checking the location of the placenta. If you do have placenta previa, your provider will discuss your options and will likely recommend ongoing monitoring to see if the placental position changes. [2] 

Treating Placenta Previa

In some cases, placenta previa may not require any treatment at all. If someone has marginal placenta previa (touching but not covering the cervix), the condition is more likely to resolve on its own before the due date. [2] If someone has complete or total placenta previa (completely covering the cervix), the condition is less likely to correct itself. If the condition is diagnosed early in the second trimester, it may correct itself as pregnancy progresses. [2] 

The goal when treating this condition is to get as close to your due date as possible and deliver the baby in the safest possible way. In most cases, this requires a c-section delivery. Your provider will take into consideration the gestational age, position of the placenta and the baby, fetal and maternal health, and other factors when moving forward with delivery. Depending on the position of the placenta and ongoing symptoms, providers may recommend the following while leading up to delivery [2]:

• Bed rest
• Reducing strenuous activities
• Avoiding intercourse, tampons, and douching
• Additional prenatal ultrasounds
• Medications
• Steroid shots, such as betamethasone 

If necessary, some may need an emergency c-section or blood transfusion to stop heavy bleeding. 

What Is Abruptio Placenta?

Abruptio placenta, also known as placental abruption, is a condition during pregnancy characterized by the placenta separating from the uterus. Placental abruption is a very serious condition that occurs in about 1 out of every 100 pregnancies. [3] Once separation occurs, it’s important to receive prompt treatment to limit or prevent any negative outcomes. 

Types of Placental Abruption

There are four different types of placental abruption [3]:

• Partial placental abruption: this occurs when the placenta doesn’t completely detach from the uterine wall.
• Complete or total placental abruption: this occurs when the placenta does completely detach from the uterine wall. 
• Revealed placental abruption: involves visible moderate to severe vaginal bleeding.
• Concealed placental abruption: involves little to no visible vaginal bleeding. This is because blood is likely trapped between the placenta and uterine wall. 

Symptoms of Abruptio Placenta

Symptoms of placental abruption can vary from person to person, but the most common sign is third-trimester vaginal bleeding accompanied by cramping. Other symptoms include [3]:

• Uterine tenderness
• Abdominal pain
• Uterine contractions
• Back pain
• Decreased fetal movement

It’s possible that there is no visible bleeding due to a concealed placental abruption. Symptoms can also resemble other pregnancy conditions, which is why seeing a healthcare provider right away is so important. 

Causes & Risk Factors of Abruptio Placenta

There is often no known cause of placental abruption. It is possible that abdominal trauma or certain lifestyle choices could lead to a detached placenta. Some factors can also put someone at a higher risk for placental abruption, including [3]:

• Trauma or injury to the abdomen or uterus (such as a fall or car accident)
• Short umbilical cord
• History of placental abruption
• Pregnant with multiples
• Underlying pregnancy complications (gestational diabetes, preeclampsia, etc)
• History of smoking or drug use
• Age 35 or older
• Uterine fibroids

Learn more about the risk factors of placental abruption → 

Diagnosing Abruptio Placenta

Placental abruption can be diagnosed through an exam and monitoring. Providers take into account your symptoms, such as how much bleeding you’ve experienced, any pain you’re feeling, when symptoms started, etc. [3] An ultrasound can give us a better idea of where the bleeding is coming from, how the fetus is doing, etc. Placental abruption is then graded as either grade 1, grade 2, or grade 3 based on the severity of symptoms. [3] 

Treating Abruptio Placenta

Unfortunately, there is no way to repair or reconnect the placenta to the uterine wall after it has detached. Treatment can vary depending on gestational age, symptoms, and severity. If the fetus is nearing full term, treatment may range from a closely monitored vaginal delivery to a c-section. [3] If the fetus isn’t close to term, your provider may recommend frequent monitoring until at least 34 weeks. Depending on maternal and fetal health, you may be able to wait a bit longer to give birth, or immediate delivery could be necessary. [3] It’s important to follow your provider's instructions closely and avoid any strenuous activities that may worsen your condition. 

Comparing Placenta Previa and Placental Abruption

Placenta previa and placental abruption share some common symptoms, however, there are many differences between the two conditions. [2-4] Not only is placental abruption seen more often than placenta previa, but placental abruptio tends to cause more severe symptoms and potential complications. [2-4] Let’s take a closer look. 

Differences in Symptoms

Both conditions can cause vaginal bleeding and may or may not be accompanied by pain in the abdomen and back. It’s also possible for someone to experience very few or no symptoms with either of these conditions. Some differences that have been highlighted by researchers include [2-4]:

• The onset of symptoms is usually sudden and intense for placental abruption but mild, gradual, and may come and go for placenta previa.
• The blood loss from placental abruption is more likely to cause anemia or shock
• Fetal movement is more likely to be impacted with placental abruption than with placenta previa

Diagnosis Approaches

Both conditions are diagnosed with the help of an ultrasound exam and monitoring. While placenta previa is often caught during routine ultrasounds, placental abruption may be caught as a result of symptoms or after an injury. In both cases, the provider will locate the placenta to check its position, look for bleeding, and determine the severity of the condition. [2-3] 

Risk Factors and Complications

For both placenta previa and placental abruption, the cause is often unknown. However, some research suggests that placental abruption is more likely to be affected by conditions occurring during pregnancy, and placenta previa is more likely to be affected by conditions that existed prior to pregnancy. [5] 

There is little that can be done to prevent either condition from occurring, however, providers recommend that all pregnant people do the following to reduce their risk of various complications [2-3]:

• No smoking, drinking, or drug use
• Maintain a healthy blood pressure
• Manage any underlying conditions
• Take health and safety precautions, such as wearing a seat belt
• Report any trauma or new symptoms to your provider
• Attend all prenatal checkups and ultrasound appointments
• Maintain healthy prenatal care, such as taking prenatal vitamins, eating a balanced diet, and drinking plenty of water
• Report any vaginal bleeding to your healthcare provider

Many risk factors are similar for both conditions and involve advanced maternal age, multiple gestation, use of illicit substances, history of fibroids, etc. 

Complications for both conditions also have some similarities and differences. For example, complications from a placental abruption include [3]:

• Premature birth
• Low birth weight
• Growth problems
• Fetal brain injury
• Stillbirth
• Blood loss
• Blood clotting issues
• Hemorrhage
• Kidney failure

Complications from placenta previa include [2]:

• Blood loss
• Premature birth
• Placenta accreta
• Placental abruption
• Low birth weight
• Fetal respiratory issues

Preparing for the Unexpected with Natalist

You can’t always predict or plan for life’s curveballs, and pregnancy complications are a great example. Even if you’re taking all the right vitamins, eating healthy meals, exercising safely, and seeing your provider regularly, complications like placenta previa and placental abruption can still arise. It can be very unsettling to read about all the things that can go wrong, but keep in mind that we have many useful resources to help us diagnose, monitor, and treat these conditions safely. My advice is to focus on what you can control, which is keeping yourself healthy and cared for through lifestyle changes and regular prenatal visits. If you’re in need of any pregnancy products or if you want to start planning ahead for postpartum, Natalist has got you covered. Shop our products here, or continue reading on the Natalist blog. 

References:

1. Herrick EJ, Bordoni B. Embryology, Placenta. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK551634/
2. Placenta Previa. Cleveland Clinic. September 2022. https://my.clevelandclinic.org/health/diseases/24211-placenta-previa#symptoms-and-causes
3. Placental Abruption. Cleveland Clinic. July 2021. https://my.clevelandclinic.org/health/diseases/9435-placental-abruption
4. Schmidt P, Skelly CL, Raines DA. Placental Abruption. [Updated 2022 Dec 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482335/
5. Yang Q, Wen SW, Phillips K, Oppenheimer L, Black D, Walker MC. Comparison of maternal risk factors between placental abruption and placenta previa. Am J Perinatol. 2009;26(4):279-286. doi:10.1055/s-0028-1103156