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Detecting Congenital Heart Anomalies In Baby During Pregnancy

Medically reviewed by Erika Rellora, MD · Obstetrics and Gynecology

Written by Lorraine Bunag, R.N. · Updated Sep 02, 2022

Detecting Congenital Heart Anomalies In Baby During Pregnancy

Children with congenital heart defects may need immediate treatment right after birth and/or life-long management of their condition. For this reason, it’s crucial to detect a possible congenital heart defect as soon as possible: while the baby is still in the womb. How do you diagnose a congenital heart anomaly of the baby during pregnancy?

Prenatal Diagnosis of CHD

Before we move further into the discussion, let’s first determine whether it’s truly possible to diagnose a congenital heart defect while the baby is still in the uterus. Experts say it is. In fact, a CDC report said that 15 % of mothers with a child who has CHD received the diagnosis while they are still pregnant. 

The report also said that the mothers are more likely to report receiving a diagnosis if:

  • They have type 1 or type 2 diabetes
  • They are over 30 years of age
  • There’s a family history of CHD
  • They have a case of multiple pregnancy (twins, triplets)
  • Their baby has another type of birth defect

How to Diagnose Congenital Heart Defects in the Baby During Pregnancy

Considering a number of mothers have received the diagnosis during their pregnancy, what are the screening tests performed to determine if a child has a congenital heart anomaly?

Routine ultrasound

Congenital heart defects may be first suspected during the routine ultrasound scan, when the doctor hears the baby’s heartbeat. 

The normal fetal heart rate is 120 to 160 beats per minute. However, fetal heart rate may deviate from this range and still be healthy:

  • Some fetuses have a heart rate of less than 90 and still be okay. 
  • It’s common for the heart rate to drop by 5 to 10 beats per minute during ultrasound. 
  • Some may have premature beats that don’t cause any problem and clear up after being born. 

Of course, detecting problematic bradycardia (slow heart rate) or tachycardia (fast heart rate) is still crucial because treatment for these can be administered while the mother is still pregnant. 

The bottom line is that ultrasound is not enough to determine the exact condition of the baby. Hence the doctor will most likely recommend a fetal echocardiography between the 18th and 22nd week of pregnancy. 

Fetal echocardiography

Fetal echocardiography is a special type of ultrasound that can show the four chambers of the heart as well as the outflow tracts. Reports say it can detect 60% to 80% of congenital heart defects, but about 30% will remain undetected until after the baby is born. Usually, undetected cases are those that are mild. 

The procedure during fetal echocardiography is the same as a routine ultrasound. 

Why the Doctor May Recommend Fetal Echocardiography

As mentioned before, fetal echo may be recommended when something shows up in the routine ultrasound. However, there are other cases when it is necessary: 

  • There is a family history of congenital heart defects, particularly when another child in the family has CHD, too. 
  • The mother is taking certain medication that increase the likelihood of the baby having a congenital anomaly. 
  • The mother has other health conditions, like diabetes, or acquired infections
  • Substance abuse by the mother
  • Other fetal screenings suggest a problem
  • The baby is conceived using assisted reproductive technology
  • The mother’s maternal age is advanced

Diagnosis After Childbirth

As mentioned earlier, about 30% of cases remain undiagnosed until after the baby is born. 

After the baby’s birth, the doctor may suspect a congenital heart disease if they spot symptoms of a cardiac problem, particularly cyanosis or the bluish discoloration of the fingernails, skin, and lips. It is also a standard operating procedure to monitor the baby for other signs of heart problems. 

Key Takeaways

Congenital heart defects can be detected while the baby is still in their mother’s womb. The most common procedure for diagnosis is fetal echocardiogram, which shows the view of the four chambers of the heart as well as the outflow tract.


Hello Health Group does not provide medical advice, diagnosis or treatment.

Medically reviewed by

Erika Rellora, MD

Obstetrics and Gynecology

Written by Lorraine Bunag, R.N. · Updated Sep 02, 2022

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