Pregnancy and Congenital Abnormalities

A congenital abnormality or genetic disorder is a health condition that a baby is born with. It can be the result of a chromosomal, hereditary, or environmental issue.

According to the U.S. Centers for Disease Control and Prevention (CDC), approximately 3% of babies are born with congenital abnormalities. The causes can be genetic or environmental. However, in some cases, the cause of a genetic disorder is not known.

Here is an overview of some of the genetic disorders that often worry parents-to-be, along with the causes, risk factors, and prenatal tests that screen for and diagnose genetic problems.

Risk Factors

Babies with congenital issues are often born to mothers who do not have any risk factors. However, the chance of having a child with an issue increases if you:

  • Are pregnant with more than one baby
  • Had exposure to something that is a known risk factor, such as drugs or certain infections
  • Have a family history of a genetic disorder
  • Have a pre-pregnancy health condition such as diabetes
  • Have a pregnancy over the age of 35
  • Have had a past pregnancy that involved a congenital abnormality
  • Used IVF and other procedures that manipulate the egg and sperm

Chromosomal Disorders

Chromosomal disorders are caused by an extra or missing chromosome. Most of the time the missing or extra chromosome cannot support life. These pregnancies typically end in miscarriage. However, there are a few chromosomal conditions a baby can be born with.

  • Down Syndrome (Trisomy 21): Down syndrome is the most common chromosomal abnormality that a baby can survive. It occurs in approximately 1 in every 600 births. The chances go up with maternal age. By the age of 45, a mom has a 1 in 45 chance of having a baby with Down syndrome. There are many services available to families with a child born with Down syndrome. With the right support, people with Down syndrome live happy, fulfilling lives.
  • Patau Syndrome (Trisomy 18) and Edward’s Syndrome (Trisomy 13): Trisomy 18 and Trisomy 13 are less frequent than Down syndrome, occurring in approximately 1 in 4,000 births. These conditions are also more severe. Babies born with these chromosomal disorders have multiple health problems including heart defects. They do not often survive their first year. 
  • Turner Syndrome: Turner syndrome is a rare disorder that is only seen in females and impacts 1 in 4,000 babies. Instead of getting two sex chromosomes, a baby with Turner syndrome just gets one X chromosome (45 X). Turner syndrome does not affect intelligence, but it does affect height and fertility. There may be some health issues, but with monitoring and treatment, women with Turner syndrome can lead a long, healthy life.
  • Klinefelter Syndrome: Another sex chromosome disorder, this one affecting males. It is an additional X chromosome (46 XXY) and shows up in approximately 1 in 500 to 1,000 baby boys. Boys with Klinefelter syndrome produce less testosterone. They are often tall and may have learning disabilities. Many boys and men with Klinefelter syndrome have only mild issues and go on to live long, healthy lives. 

Hereditary Disorders 

Hereditary disorders are passed down from parents to their children. Most of the time, hereditary conditions are recessive, which means that two genes (one from each parent) are needed for the disorder to show up in the baby.

If there is only one gene, the person is a carrier and does not have the disease. If both parents are carriers, the chances of passing the disorder on are much higher. 

Different ethnic groups are more likely to carry genes for specific genetic disorders. When parents are from the same ancestral background, the chances of having a child with certain genetic conditions goes up. However, even though these disorders are more common among specific groups, they are still rare.

  • Cystic Fibrosis (CF) is a rare genetic disorder that is more common among people of European ancestry. Cystic fibrosis affects the lungs and other organ systems. It is seen in around 1 in 3,500 white newborns and less frequently in other ethnic groups.
  • Sickle-Cell Anemia is the most common hereditary disorder in people of African descent. Sickle-cell disease affects red blood cells and occurs in approximately 1 in 70,000 Americans. However, the rate is 1 in 500 among African Americans.
  • Tay-Sachs Disease is typically found in people with certain ancestries, such as Eastern European Jews, but it has also been found in other groups such as French Canadians. Tay-Sachs causes damage to the nerves in the brain and spinal cord. In the general population, about 1 in 320,000 babies are born with Tay-Sachs. 
  • Beta Thalassemia is a genetic disorder found more commonly in people from the Mediterranean region. Beta thalassemia is a blood disorder that leads to anemia because it affects how the body makes red blood cells. It occurs in approximately 1 in 10,000 births in the European Union, but it's much rarer in the general population, showing up at a rate of 1 in 100,000 births.

Environmental Abnormalities

A teratogen is something that affects the growth and development of a fetus during pregnancy. Exposure to a teratogen during pregnancy can lead to a congenital abnormality.

Substances and infections such as alcohol, drugs, certain medications, chickenpox, rubella, syphilis, or toxoplasmosis can affect a baby’s development. The nature of the effect depends on other factors, such as:

  • The stage of pregnancy you’re in (the first trimester is usually the most vulnerable)
  • How much of the toxin you’re exposed to
  • How long the exposure lasts

Exposure to toxins from your environment can affect every system of your baby’s body including the head, facial features, brain function, nervous system, heart, sight, hearing, and bones. It can even lead to death.

Detecting Abnormalities

During your pregnancy, you can have tests to screen for congenital abnormalities. If you are over the age of 35 or have other risk factors, your doctor might recommend additional testing.

Some of the screening tests you might be offered during your pregnancy include:

  • Nuchal Translucency (NT Scan)
  • First Trimester Blood Tests: Maternal serum-free hCG and pregnancy-associated plasma protein-A (PAPP-A)
  • Chorionic Villus Sampling (CVS) 
  • Second Trimester Quad Screen Blood Test: Maternal serum alpha-fetoprotein (MSAFP), hCG, unconjugated estriol (uE3), and dimeric inhibin-A
  • Level II Ultrasound
  • Amniocentesis 

Genetic Counseling

A genetic counselor is a doctor or trained medical professional who gives you information about your risk of having a child with a congenital disorder. They can provide you with preconception counseling or counsel you during your pregnancy. 

Genetic counselors take information about your family history, health, and medical history. While you’re pregnant, they gather information from screening tests and follow your baby’s growth. They can detect any genetic problems and provide you with information on a specific disorder, it’s course, and management.

You do not need a reason to seek genetic counseling before becoming pregnant, but genetic counseling is recommended if: 

  • The result of a prenatal screening test or an ultrasound shows the need for counseling
  • You and your partner are related and from the same family line
  • You are a known carrier of a chromosomal or genetic disorder
  • You are of advanced maternal age
  • You had a stillbirth or a newborn who passed
  • You have a family history of a specific genetic disorder
  • You have a family history of chromosomal abnormalities
  • You have been exposed to an illness, infection, or environmental toxin that could affect your baby
  • You have had recurrent miscarriages

What to Do

Learning that the child you’re carrying has a congenital abnormality can be devastating. Depending on the disorder, it may mean only minor health concerns for the child, or it could be something that will have a life-long effect on your family.

There will be difficult decisions to make, and it can certainly be scary. However, there are also steps you can take to make the process easier.

  • Talk to your doctor and a genetic counselor. Ask questions and get all the information you can about the diagnosis, including what you need to know about management and treatment. Go over your options and take the time to think about and process all the information. 
  • Sorrow and anger are normal. Whether you have to say goodbye to your child or you’re grieving the loss of the child you expected to have, take the time to work through your emotions. Talk openly about your feelings with your partner, family, friends, or mental health professional. If you will be experiencing the loss of a child, counseling can help you through the process of grieving. If you are having a child who will have health concerns, seeking counseling before you deliver will help you prepare for, accept, and bond with your special needs child after they are born.
  • Talk to your partner about how you feel, but also make sure to let your partner express their feelings to you. Lean on and support each other. 
  • Learn all you can about your child’s condition. The more you know, the more you can do to prepare for a special needs child, arrange services, and help your child get the best start in life.
  • Join a support group and seek out friends and family who can give you the support you need as you come to terms with your child’s condition. There are resources you can connect and work with to get your child the services and support they need. 
  • Find out what services are available to you and your child before they arrive. After you have your baby, speak with a social worker and case manager in the hospital, as they can provide additional referrals. Early intervention can help you set up what your family needs.

A Word From Verywell

It’s normal to worry about the health of your baby while you are pregnant—especially if you are an older mom, you have a known genetic risk factor, or you have a family member with a specific genetic health condition. It can also be stressful to go through routine prenatal screenings and have to wait for results.

Keep in mind that 97% of babies are born healthy. If your baby is in the 3% born with a congenital issue, there are treatment options and services available. Together with your baby’s doctors, you can make the right decisions for your family, manage your baby’s health needs, and plan the best possible life for your child as they grow up.

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Article Sources
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