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Prenatal Screening program

Pregnant Individual on a Bench

Genetic Conditions and Birth Defects Screened for 

Most babies are born without any type of genetic condition or birth defect. But with all pregnancies, there is a 3 to 4 out of 100 chance for this to happen.

The California Prenatal Screening (PNS) Program screens for the genetic conditions and birth defects described on this page. Please consult with your prenatal care provider or genetic counselor on whether to get prenatal screening. You decide whether to get prenatal screening or not. 

If a screening result indicates an increased chanceā€‹ of a specific genetic condition or birth defectā€‹, diagnostic testing is needed to tell whether the fetus has that condition or defect.

If diagnostic tests show that your baby has a genetic condition or birth defect, a prenatal care provider or genetic counselor at a state-approved Prenatal Diagnosis Center (PDF) will give you information. They will discuss the genetic condition or birth defect and options for your pregnancy.

Genetic Conditions

  • Down syndrome (trisomy 21)
  • Trisomy 18
  • Trisomy 13
Starting April 1, 2024, the CA PNS Program will add sex chromosome aneuploidies (SCAs) ā€“ also referred to as X and Y chromosome variations ā€“ to the state cell-free DNA screening panel.ā€‹

  • ā€‹Turner syndrome
  • Klinefelter syndrome
  • Trisomy X
  • XYYā€‹

Birth Defects

  • Neural Tube Defects (they affect the brain, spine, or spinal cord)

Below is more information on the genetic conditions and birth defects screened for by the PNS Program.

Frequently Asked Questions

Trisomy 21, also called Down syndrome, is a condition in which a baby is born with an extra chromosome. Chromosomes are small "packages" of genes in the body. Genes are pieces of code passed down from parents to children. They make us who we are.

Chromosomes determine how a fetus forms during pregnancy, functions as it grows in the womb, and after birth. Typically, a baby is born with 46 chromosomes. Babies with Down syndrome have an extra copy of one of these chromosomes, chromosome 21. A medical term for having an extra copy of a chromosome is ā€œtrisomy.ā€ This extra copy changes how the fetusā€™s body and brain develop, which can cause both mental and physical challenges for the baby.

Even though people with Down syndrome might act and look similar, each person has different abilities. People with Down syndrome usually have an IQ (a measure of intelligence) in the mildly-to-moderately low range and are slower to speak than other children.

Down syndrome can affect babies born to women of any age. However, as women get older, the chances increase for having a baby with Down syndrome.

Content provided by the Centers for Disease Control and Prevention (CDC) and GDSP. For information and references about trisomy 21, please visit: Facts about Down Syndrome

Recommended Resources

Parent Support Groups

Data Sheet

What Conditions are Commonly Tested for During Pregnancy? Video:

 

Transcript (PDF)
What Conditions Are Commonly Tested for During Pregnancy? Genetic Support Foundation/Washington Department of Health, 4.32 minutes. Please note that this video covers structural defects and sex chromosome changes that the PNS Program does not screen for. 

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