Bicornuate Uterus Effects on Pregnancy

A bicornuate uterus can cause pregnancy loss and preterm labor

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A bicornuate uterus, also known as a heart-shaped uterus, is a malformation identified at birth in about 4 of every 1,000 people with uteruses. Normally, the endometrial cavity or space inside the uterus resembles an upside-down triangle. With a bicornuate uterus, the top uterine wall (fundus) dips downward in the middle, giving the space within the uterus a heart shape.

While people with a bicornuate uterus can have a successful pregnancy, the condition increases the risk of infertility, repeat miscarriage, and pregnancy complications, including preterm labor. 

Continue reading to learn more about a heart-shaped uterus and pregnancy, including how to treat bicornuate uterus and what to do if you’re diagnosed with the condition once you’re pregnant. 

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Bicornuate Uterus: Effect on Pregnancy

A bicornuate uterus makes it more difficult to get pregnant and to carry a pregnancy to term. The condition is about 2.5 times more common among those with infertility than the general population. It’s about 5 times more common in those who have had miscarriages and more than 10 times more common in those who have both infertility and a history of miscarriage.

A bicornuate uterus also increases risk of pregnancy complications, including:

The risk for some of these conditions was more than 250% higher for people with a bicornuate uterus than for people without one. People with the condition are also at higher risk for complications after delivery, including needing a hysterectomy (surgical removal of the uterus) or blood transfusion

It can be scary to hear about the complications that a bicornuate uterus can cause. Yet it’s important to keep it in perspective. Many with bicornuate uteri can carry pregnancies to term. One study found that more than 62% of people with this condition will have a healthy delivery. Talk to your healthcare provider about your risks and how to increase the odds of conception and healthy delivery. 

Shape of Bicornuate Uterus

All bicornuate uteruses have a heart shape. But there are different types of severity of the condition. In mild cases, the upper wall of the uterus dips only slightly. In more severe cases, the wall extends deeply downward, nearly splitting the uterus in two. 

In addition, there are two subtypes of bicornuate uteri:

  • Bicornuate bicollis: Occurs when the separation expends to the cervix, or entrance to the uterus, resulting in two separate cervixes
  • Bicornuate unicollis: Occurs when the separation doesn’t reach the cervix, resulting in a partitioned uterus but only one cervix 

Cause of Bicornuate Uterus

A bicornuate uterus forms in a fetus when the Mullerian ducts are develop in the reproductive tract, which includes the uterus. The medical community understands that a bicornuate uterus and other uterine abnormalities can occur when something interferes with this developmental process. However, the exact reasons why this happens are not clearly understood.

A bicornuate uterus forms as a fetus is developing. But many people don’t find out they have one until they try to get pregnant or experience a miscarriage. 

Symptoms Associated With Bicornuate Uterus

Most people with a bicornuate uterus don’t know they have the condition until pregnancy. Others may experience heavy menstrual bleeding or pain during sex, but most people have no symptoms of the condition until they’re pregnant. 

During pregnancy, the symptoms of a bicornuate uterus can include:

  • Miscarriage (loss of pregnancy before 20 weeks), including repeat miscarriage
  • Trouble conceiving, although many people with a bicornuate uterus get pregnant without intervention
  • Pregnancy complications

How Do You Know You Have a Bicornuate Uterus?

Most people with a bicornuate uterus don’t know they have the condition until they experience repeated miscarriages or until the abnormality is detected during a routine ultrasound during pregnancy.

If your healthcare provider suspects a bicornuate uterus or another uterine abnormality they’ll likely recommend imaging procedures to confirm the shape of your uterus. These can include:

  • Ultrasound, particularly three-dimensional ultrasound, which is particularly effective at diagnosing bicornuate uterus. 
  • A magnetic resonance imaging (MRI) scan
  • Sonohysterogram, a procedure in which saline is inserted into the uterus and an ultrasound is used to get a better picture of the shape of the inside and outside of the uterus

When to Consider Treatment for a Heart-Shaped Uterus

If you’re already pregnant when you’re diagnosed with a bicornuate uterus, there’s nothing that can be done until after delivery. In this case, your healthcare providers will closely monitor you to ensure that you and your baby stay healthy throughout the pregnancy. A bicornate uterus may create tighter fit for a newborn to pass through, so your healthcare provider may recommend a c-section.


Bicornuate uterus is a malformation that about 4 in 1,000 people with a uterus are born with. It causes a heart-shaped uterus and uterine cavity and in some cases can divide the uterus and cervix into two.

People with a bicornuate uterus often don’t know they have the condition until they experience miscarriage or infertility. During pregnancy, the condition can lead to complications including pregnancy loss and early labor. If you're diagnosed during pregnancy, there is no treatment, so you'll get additional monitoring to ensure that you and your baby are healthy. Most people with bicornuate uteri go on to deliver healthy babies.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Kelly Burch
Kelly Burch is has written about health topics for more than a decade. Her writing has appeared in The Washington Post, The Chicago Tribune, and more.