Mirror Syndrome

Mirror syndrome, also known as Ballantyne syndrome, is an extremely rare and serious condition in which both a pregnant person and fetus experience severe fluid buildup. The condition is called “mirror syndrome” because both the pregnant person and fetus develop similar symptoms, such as swelling (edema) in the pregnant person’s body and placenta and fluid buildup (hydrops fetalis) in the fetus. It’s believed that mirror syndrome may be a result of the pregnant person’s immune response to health complications in the fetus.

Symptoms of mirror syndrome may include:

In the pregnant person:

• Severe swelling (edema) of the face, limbs, and abdomen
• High blood pressure and protein in urine (signs of preeclampsia)
• Excessive weight gain due to fluid retention
• Decreased urine output
• Shortness of breath or difficulty breathing caused by fluid buildup in the lungs (pulmonary edema)
• Blurred vision
• Upper abdominal (epigastric) pain
• Eclampsia in rare, severe cases
• Placental abruption

In the fetus:

• Hydrops fetalis
• Severe swelling (edema)
• Heart failure or abnormal heart function
• Intrauterine fetal demise in rare occasions

While the exact cause of mirror syndrome isn’t fully understood, it begins with fetal hydrops, where the fetus accumulates abnormal fluid in areas like the abdomen, lungs, or under the skin, often due to poor placental blood flow. This impairs the fetus’s ability to receive nutrients and oxygen, leading to fluid buildup. In response, the placenta releases cytokines, triggering a series of reactions in the pregnant person’s body that affect fluid balance and blood pressure.

As the fetus faces these challenges, the pregnant person’s body tries to compensate, leading to fluid retention, swelling (edema), and high blood pressure, similar to preeclampsia. This is the "mirror" part of mirror syndrome — what happens to the fetus begins to affect the pregnant person in a similar way.

Whenever fetal hydrops is diagnosed by prenatal ultrasound, signs of mirror syndrome should be closely monitored. Doctors typically diagnose mirror syndrome when the pregnant person carrying a hydropic fetus shows signs of edema and elevated blood pressure.

In addition to a physical exam, doctors will order tests to evaluate the pregnant person and fetus. These may include:

• Blood tests to monitor the pregnant person’s kidney and liver function, and protein levels in their urine
• Fetal ultrasound and monitoring to assess the fetus’s heart rate and check for signs of distress

Treating mirror syndrome involves managing the health of the pregnant person and the fetus and preventing complications. Measures include:

• Continuous monitoring of the fetus’s heart rate and the pregnant person’s health
• Fetal intervention in cases of reversible hydrops (i.e. fetal anemia, TTTS, etc.)
• Medications to control the pregnant person’s blood pressure, reduce swelling, prevent seizures, and help with fetal lung development
• Delivery to provide immediate care in cases where the fetus’s condition worsens, or the pregnant person’s symptoms become severe

At Boston Children’s Hospital, our Fetal Care and Surgery Center works closely with your existing prenatal care team to create a personalized treatment plan tailored to your needs when managing mirror syndrome. Our goal is to ensure you receive the best possible care before, during, and after delivery.

With mirror syndrome, the long-term outlook for both the pregnant person and the fetus depends on the severity of the underlying conditions and how well they are managed during pregnancy. If treated promptly, symptoms of mirror syndrome, such as swelling in the pregnant person, usually resolve after delivery. However, severe cases may lead to complications, including preeclampsia or organ damage.

For the fetus, outcomes depend on the underlying cause of the hydrops fetalis and the timing of delivery. In some cases, hydrops can resolve after birth, but in more severe cases, an early delivery and intensive neonatal care may be necessary.

Mirror syndrome is a serious pregnancy complication that can jeopardize both maternal and fetal health. At Boston Children's, we’re dedicated to providing the highest level of care and support to patients and families experiencing mirror syndrome to prevent these life-threatening complications.

Our Fetal Care and Surgery Center includes a team of specialists who provide comprehensive care for both the fetus and the pregnant person in cases of mirror syndrome. The team includes fetal surgeons, maternal-fetal medicine specialists, neonatologists, obstetricians, and other experts who work together to develop a personalized treatment plan. We provide advanced diagnostic fetal imaging, fetal monitoring, and medical and surgical interventions. In cases where delivery is necessary, our neonatal care team is prepared to provide immediate support, including treatments for hydrops and other complications.