Pregnancy and Congenital Abnormalities

How often they occur, risks, causes, screening, and information

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. Congenital issues can be genetic or environmental, but sometimes the cause of a disorder is not known. According to the U.S. Centers for Disease Control and Prevention, approximately 3 percent of babies are born with congenital abnormalities.

Here you will find information about some of the genetic disorders that worry pregnant moms, 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 moms who don't have any risk factors at all. However, the chance of having a child with an issue goes up with: 

  • Pregnancy over age 35
  • A family history of a genetic disorder
  • Having a past pregnancy that involved a congenital abnormality
  • Exposure to something that is known to cause issues such as drugs or certain infections
  • The use of IVF and other procedures that manipulate the egg and sperm
  • Being pregnant with more than one baby
  • Pre-pregnancy health conditions such as diabetes

Chromosomal Disorders

Chromosomal disorders are caused by an extra or missing chromosome. Most of the time a missing or extra chromosome cannot support life, so those pregnancies end in miscarriage. But there are a few chromosomal conditions that a baby can have at birth.

  • 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 age, so by the age of 45, a mom has a one in 45 chance of having a baby with Down syndrome. There are many services available to children born with Down syndrome to help improve their quality of life. There may be challenges, but with support, people with Down syndrome can 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, but they are also more severe conditions. 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. But, if both parents are carriers, the chances of passing the disorder on is much higher. 

Different ethnic groups throughout the world 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 found more commonly among people of European ancestry. Cystic fibrosis affects the lungs and other organ systems of the body. 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 an inherited disease that affects those of Jewish descent. 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.
    How Genetic Disorders Are Inherited

    Environmental Abnormalities

    A teratogen is something that affects the growth and development of a baby during pregnancy. Exposure to a teratogen during pregnancy can lead to a congenital abnormality. Substances and infections such as alcohol, drugs, certain medications, chicken pox, rubella, syphilis, or toxoplasmosis can affect the baby’s development depending on:

    • 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 the 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 pregnancy, many tests screen for congenital abnormalities. If you are over 35 or have other risk factors, your doctor will talk to you about additional testing. Some of the screening tests you may have during 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 help detect a genetic issue and provide information on each 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: 

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

    What to Do

    Learning that the child you’re carrying has a congenital abnormality can be devastating. Depending on the type of disorder, it may mean only minor issues for a child, or it could be something that will have a life-long effect on you, your child and your family. There will be difficult decisions to make, and it can certainly be scary.

    However, there are many appropriate steps to take and keep in mind after learning your baby is at risk for or has a genetic disorder:

    • Talk to your doctor and a genetic counselor. Ask questions and get all the information you can about the diagnosis and how it will affect your baby. 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 “perfect child.” Take the time to work through your emotions and talk about your feelings with your partner, family, friends, or a professional. If you will be experiencing the loss of your child, it will help you get through it. If you are having your child, it will help you better prepare to accept and bond with your special needs child after delivery. 
    • Talk to your partner about how you feel and let your partner express his 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 the friends and family who can give you the support you need as you come to terms with your child’s condition and work to get your child all the services and support they need. 
    • Find out all you can about the services available to you and your child before your child is born. When you have your baby, talk to the social worker and case manager in the hospital for additional referrals. Early intervention can help your child’s quality of life. 

    A Word From Verywell

    When you’re pregnant, it’s normal to worry about the health of your baby, especially when you are an older mom or you have a family member who has a health condition. It’s also stressful and worrisome as you go through routine prenatal screenings and have to wait for results. But keep in mind that 97 percent of babies are healthy, and if your baby is in the 3 percent 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 issues, and plan for the best possible life for your child and your family.

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    Article Sources
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