Pregnancy-Related Fears: Know the Facts about Birth Defects

Pregnant woman

You’re pregnant – congrats! As a new mom-to-be, you may experience a range of emotions from joy to excitement to “Worrier in Chief” – all in a matter of minutes – as reality starts to sink in.

You are not alone.

One of the things pregnant women tend to worry about the most are birth defects. In fact, according to Parents Magazine, 78 percent of expectant mothers rated birth defects as their number one concern. But knowing the facts can help ease your anxiety. And there are steps you can take to prevent birth defects and protect your baby.

Genetic Counselor Catherine Burson from the Center for Maternal Fetal Health at Rocky Mountain Hospital for Children, an affiliate of HCA Healthcare, hopes to help relieve any potential angst with some of the most frequently asked questions below.

What are the most common types of birth defects?

CB: Birth defects are structural changes present at birth that can affect almost any part or parts of the body (e.g., heart, brain, foot). They may affect how the body looks, works, or both. Here are a few of the birth defects that are most commonly seen:

  • Heart: Congenital heart defects, which changes the normal flow of blood through the heart, are the most common type of birth defect. They affect 8 out of every 1,000 newborns. Each year, more than 35,000 babies in the United States are born with congenital heart defects. There are many types of congenital heart defects ranging from simple defects with no symptoms to complex defects with severe, life-threatening symptoms.
  • Central nervous system (CNS): The most common CNS defect is spina bifida, occurring in about 1 in 2,858 live births. This occurs when the neural tube (protective case around spinal cord) fails to close all of the way often resulting in damage to the spinal cord and nerves.
  • Chromosomal: These defects involve the number of chromosomes a baby has. Typically, each parent contributes 23 of their own chromosomes totaling 46. Sometimes an extra chromosome is added or one is missing resulting in birth defects. The most common chromosomal defect is Trisomy 21, or Down syndrome, which occurs in 1 in 691 live births. Genetic testing may also show smaller regions of the chromosomes that are missing or extra; these are typically very rare and specific to the genes involved in that region.
  • Cleft lip and/or palate: These birth defects involve improper formation of the lips and/or palate during pregnancy. This happens in 1 in 940 live births.

How many babies are affected by birth defects?

CB: Less than five percent of all newborns in the United States will have a major structural birth defect. That’s roughly 120,000 babies each year.

When/how are birth defects typically diagnosed? In utero, at birth, after? Explain.

CB: The technologies involved in diagnosing birth defects are constantly improving and many birth defects can be detected earlier today than ever before. The timeframe for diagnosis often is dependent upon what type of birth defect a baby has.

Testing of mom’s blood between 10-20 weeks can be done to see if levels suggest a baby has a birth defect of the central nervous system (such as spina bifida). During this time, other tests can also be conducted on mom’s blood that screen for many of the more common genetic syndromes like Down syndrome, for example.

Ultrasounds can visualize many birth defects as well as check baby for appropriate growth. If any of those screening tests show that the baby is at a higher chance of having a genetic syndrome, then genetic testing like chorionic villus sampling or amniocentesis are available. This allows for diagnosis of birth defects in which the genetic causes are well understood.

Although most birth defects can now be seen prenatally, sometimes a baby is born with something that wasn’t detected before birth.  Testing can always be done after birth, as well.

Are birth defects genetic?

CB: Most isolated birth defects are caused by a combination of many different factors not all of which are well understood.  However genetics certainly are a part of that combination!  If a baby has multiple birth defects, then it is more likely that a genetic cause will be found.  Sometimes coming up with an explanation is a long process involving many tests.  Sometimes the answer is never found.

So then, what are the primary causes of birth defects?

CB: Birth defects can occur during any stage of pregnancy. Most birth defects occur in the first three months of pregnancy, when the organs of the baby are forming. This is a very important stage of development. However, some birth defects occur later in pregnancy. During the last six months of pregnancy, the tissues and organs continue to grow and develop.

For some birth defects, like Fetal Alcohol Syndrome, we know the cause – drinking alcohol during pregnancy. But for most birth defects, we don’t know what causes them; although, we think they are caused by a complex mix of factors including our genes (information inherited from our parents), our behaviors, and things in the environment. But, we don’t fully understand how these factors might work together to cause birth defects.  

We know the following can put women at higher risk of having a child with a birth defect.

  • Smoking, drinking alcohol, or taking certain “street” drugs during pregnancy.
  • Having certain medical conditions, such as being obese or having uncontrolled diabetes before and during pregnancy.
  • Taking certain medications, such as isotretinoin (a drug used to treat severe acne).
  • Having someone in your family with a birth defect. To learn more about your risk of having a baby with a birth defect, you can talk with a clinical geneticist or a genetic counselor.
  • Being an older mother, typically over the age of 34 years.

How can birth defects be prevented?

CB: Not all birth defects can be prevented. But there are things that a woman can do before and during pregnancy to increase her chance of having a healthy baby:

  • Be sure to see your healthcare provider regularly and start prenatal care as soon as you think you might be pregnant.
  • Get 400 micrograms (mcg) of folic acid every day, starting at least one month before getting pregnant.
  • Don’t drink alcohol, smoke, or use “street” drugs.
  • Talk to a healthcare provider about any medications you are taking or thinking about taking. This includes prescription and over-the-counter medications and dietary or herbal supplements. Don’t stop or start taking any type of medication without first talking with a doctor.
  • Learn how to prevent infections during pregnancy. (For example, avoid active Zika areas and/or protect against mosquitos, wash your hands frequently, don’t change dirty cat litter, stay away from wild animals and their waste, get STD testing done, avoid unpasteurized milk, soft cheeses and certain types of meats)
  • If possible, be sure any medical conditions are under control, before becoming pregnant. Some conditions that increase the risk for birth defects include diabetes and obesity.

Any advice for parents living with children affected by birth defects?

CB: Babies who have birth defects often need special care and interventions to survive and to thrive developmentally. Early intervention is vital to improving outcomes for these babies. If your child has a birth defect, you should ask his or her doctor about local resources and treatment. Geneticists, genetic counselors, and other specialists are another great resource.

If you’re thinking about getting pregnant, what tips would you recommend for a healthy pregnancy?


  • Make sure immunizations are up to date
  • Take a prenatal vitamin (especially folic acid) even before you get pregnant
  • Get consistent prenatal care
  • Exercise
  • Avoid risk factors
  • Know when to call your doctor with concerns
  • Askabout/manage chronic health conditions or medications prior to getting pregnant

January is National Birth Defects Prevention Month. Rocky Mountain Hospital for Children is part of the HealthONE family, a division of HCA Healthcare, in Denver.

About HCA Healthcare

HCA Healthcare, one of the nation's leading providers of healthcare services, is comprised of 183 hospitals and more than 2,300 sites of care, in 20 states and the United Kingdom. Our more than 283,000 colleagues are connected by a single purpose — to give patients healthier tomorrows.

As an enterprise, we recognize the significant responsibility we have as a leading healthcare provider within each of the communities we serve, as well as the opportunity we have to improve the lives of the patients for whom we are entrusted to care. Through the compassion, knowledge and skill of our caregivers, and our ability to leverage our scale and innovative capabilities, HCA Healthcare is in a unique position to play a leading role in the transformation of care.

Recent articles