Placenta Previa: What It Is, Types, Causes, And Treatment

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During pregnancy, the placenta is developed in the uterus as an important organ to provide nourishment and protection to your baby. In some pregnancies, it can become tethered to the lower section of the uterus, causing a pregnancy-related complication called placenta previa, or low-lying placenta. However, mostly the placenta is attached to the top or side of the uterus by the umbilical cord (1). Read this post to know more about placenta previa, how it affects your pregnancy and your baby, and a few strategies to correct or manage it for safe and healthy childbirth.

What Is Placenta Previa?

Placenta previa is a pregnancy complication that occurs when the placenta lies low in the uterus and covers a part, or the entire cervix, which is the opening to the birth canal (2).

Placenta previa occurs in one out of 200 pregnancies (3). The condition is not a concern if it happens in the early stages of pregnancy. But if it occurs during labor and delivery, it could lead to complications that can harm both the mom and the baby.

What Are The Types of Placenta Previa?

  • Marginal previa, where the placenta borders the cervix
  • Partial previa, where the placenta covers only a part of the cervical opening
  • Complete previa, where the placenta covers the cervix entirely

Types of Placenta Previa

The condition can be further classified into anterior and posterior placenta previa, which refers to the exact placental position within the uterus. It can be defined through an ultrasound scan (4) (5).

What Are The Causes Of Placenta Previa?

The actual cause of placenta previa is unknown. But some factors can increase the likelihood of this condition (6).

Risk factors that increase the chances of a low-lying placenta include:

  • Previous surgeries of the uterus, such as a C-section, D&C (dilation and curettage) or uterine fibroid removal
  • Second or subsequent pregnancy
  • Advanced maternal age
  • Carrying twins, triplets or more

However with most cases, sometimes there are no risk factors.

These risks cannot be controlled. Others that can be controlled to prevent placenta previa include:

  • Smoking
  • Cocaine consumption (2)

Knowing the symptoms of this condition could help in an early diagnosis.

What Are The Symptoms and Signs Of Placenta Previa?

The signs and symptoms of placenta previa differ from one pregnant woman to another. While some do not experience any symptoms, others show warning signs such as (7):

  • Sudden onset of painless, bright red vaginal bleeding that can range from light to heavy.
  • Early labor symptoms such as regular contractions, pain in the belly, or lower back.

You must call your doctor immediately if you notice vaginal bleeding during your pregnancy, irrespective of the trimester.

If you do not experience any symptoms, your doctor may be able to identify a placenta previa during your regular prenatal ultrasound scans.

How Is Placenta Previa Diagnosed?

Placenta previa is diagnosed by ultrasound. Most cases are detected during the second-trimester checkup when you have a routine ultrasound test. The diagnostic tests include (8):

If your doctor detects placenta previa, there will be activity restrictions placed.

Here are some questions your doctor may ask to confirm the diagnosis:

  • When did you first notice vaginal bleeding?
  • Was the bleeding only once, or was it recurring?
  • Do you have any pain or contractions?
  • Is the bleeding heavy?
  • Did you undergo any surgeries such as fibroid removal, cesarean, D&C, or abortion?
  • Is this your first pregnancy?
  • How long does it take to reach the hospital in case of an emergency?
  • Do you smoke?
  • Is there anyone who can accompany you when required?

If the diagnosis is confirmed, you can ask your doctor these questions:

  • Is there a chance of the condition resolving on its own?
  • How do I take care of myself?
  • How can I manage the bleeding?
  • What symptoms should prompt me to go to the hospital?
  • When should I revisit the hospital?
  • Will a placenta previa increase the chances of complications in future pregnancies?
  • Can I deliver vaginally?

In addition to this, your doctor may also give you care instructions and precautions to take when you have a placenta previa.

How Is Placenta Previa Treated?

There are no medical or surgical treatments for curing placenta previa (8). However, the condition can be managed by alleviating the bleeding and discomfort (2).

Management and treatment depend on some factors:

  • The health of the mother and the baby
  • The position of the baby
  • The location of the placenta
  • The amount of blood loss
  • The gestational age of the baby
  • The type of placenta previa

If you are diagnosed with placenta previa before the 20th week of pregnancy, it is likely to resolve. The placental position can change with the growing uterus and can move away from the cervix.

If it does not resolve or placenta previa is diagnosed in the later stages of pregnancy, your doctor will most likely suggest a C-section. If a previa is detected on your 18-20 week ultrasound, a follow-up ultrasound is usually recommended around 28 weeks, and if still present, around 32-34 weeks.

What To Do When

You are not bleeding or bleeding lightly

  • Be prepared to go to the hospital if bleeding turns heavy or resumes.
  • If the placenta is placed low but is not covering the cervix, your doctor may suggest a vaginal delivery.

You are bleeding heavily

  • Go to the doctor immediately as blood transfusion may be necessary in the case of severe bleeding (9).
  • The doctor prescribes steroids if you are not nearing the due date, or haven’t reached the 37th week, to prepare the baby by speeding up the development of his or her lungs.
  • The OB/GYN will plan a cesarean if you are past the 36th week (10).

Your bleeding does not stop

  • Emergency cesarean, even if you are not nearing the due date.

These are situations when you need to visit the doctor immediately, to prevent any harm to you or your baby.

Precautions For Low-Lying Placenta

These precautions help you avoid further complications caused by a low-lying placenta (2).

  • Avoid strenuous activities, such as intense cardio exercise or lifting weights
  • Avoid sexual intercourse
  • Take bed rest

Precautions are important because placenta previa can lead to some serious complications.

What Are The Complications Of Placenta Previa?

Some possible complications of placenta previa include (5):

  • Hemorrhage (heavy bleeding)
  • Fetal distress from lack of sufficient oxygen
  • Premature birth that is before the 37th week of pregnancy
  • Birth defects
  • Slowed baby growth
  • Health risks to the baby
  • Emergency C-section
  • Hysterectomy, when the placenta fails to deliver from the uterine lining
  • Placenta accreta, where the placenta attaches deep into the uterine wall and mandates a hysterectomy at the time of delivery

While you cannot correct a low-lying placenta, you can manage the condition. Next, we’ll tell you how.

How To Cope With Placenta Previa?

Here is how you can do it:

  1. Learn everything about the condition: Having clarity about the condition eliminates unwanted doubts, fears, and anxiety. Talk to your doctor or connect with others (you can find in support groups) who have the same condition.
  1. Prepare for cesarean section: Placenta previa makes vaginal delivery impossible and dangerous. Therefore, a cesarean delivery will become necessary for your baby’s and your well-being.
  1. Rest: You may not like the idea of bed rest, but you need it at this time. Use the free time to pursue a hobby or read about baby care and shop online.

How To Prevent Placenta Previa?

There is no way to prevent placenta previa since there is no particular cause for it.

However, if the risks for you are high owing to your age, prior surgeries, or previous pregnancies, try to be extra careful and maintain a healthy lifestyle. Most importantly, stay away from cigarette smoking and cocaine consumption as they are associated with the condition.

Next, we answer a few commonly asked questions about placenta previa.

Frequently Asked Questions

1. Is placenta previa genetic (hereditary)?

No, placenta previa is an obstetric complication and not a genetic condition (2).

2. Can I fly with a low-lying placenta?

Avoid flying to avoid bleeding while in flight travel.

If diagnosed with placenta previa, remain vigilant for any vaginal bleeding. Visit the clinic as instructed by the doctor. Avoid strenuous activities during the pregnancy. If you’ve undergone uterus-related surgeries in the past or have an increased risk of placenta previa, keep your doctors informed at an early stage. Placenta previa is a concerning condition that may increase your anxiety until the delivery. But proper rest and medical attention could help you deliver a healthy baby. Hence, visit the hospital as directed and rest well.

References:

MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
1. What is the placenta?; Pregnancybirthbaby
2. Placenta previa; The National Library of Medicine;
3. Mabie WC; Placenta previa; Department of Obstetrics and Gynecology, University of Tennessee, Memphis.
4. Shumaila Zia; Placental location and pregnancy outcome; J Turkish-German Gynecol Assoc 2013
5. Frances M. Anderson-Bagga and Angelica Sze.; Placenta Previa
6. Placenta Previa; The University of Rochester Medical Center
7. Robert K. Stoelting, et al.; Placenta Previa; Stoelting’s Anesthesia and Co-existing Disease
8. Bleeding in Pregnancy/Placenta Previa/Placental Abruption; The Children’s Hospital of Philadelphia
9. Placenta Previa; Stanford Children’s Health
10. Heller HT, et al.; Outcomes of pregnancies with a low-lying placenta diagnosed on second-trimester sonography
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Rebecca Malachi

Rebecca is a pregnancy writer and editor with a passion for delivering research-based and engaging content in areas of fertility, pregnancy, birth, and post-pregnancy. She did her graduation in Biotechnology and Genetics from Loyola Academy, Osmania University and obtained a certification in ‘Nutrition and Lifestyle in Pregnancy’ from Ludwig Maximilian University of Munich (LMU). She has been into health and... more

Dr. Christian Pope

(DO, FACOG)
Dr. Christian Pope is Board-certified in Obstetrics & Gynecology, and a Fellow of the American Academy of Obstetricians and Gynecologists. He is a long-standing medical staff member and past chairman of Obstetrics and Gynecology at St. Luke's Hospital of SouthCoast Hospitals in New Bedford, Massachusetts and is in private group practice at Hawthorn Medical Associates, Inc. He is a member... more