MedBlog

Your Pregnancy Matters

Newborn screening gives babies a head start for a healthier future

Your Pregnancy Matters

Person wearing medical gloves holds heel of newborn
The newborn heel stick test is painless for babies and gives essential information about their future health and family reproductive planning.

A baby’s first few weeks of life are bustling with snuggles and visitors as well as screenings and benchmarking exams. Along with the newborn critical congenital heart disease and hearing screening, all babies get a heel stick screening to check for dozens of metabolic or genetic conditions, including cystic fibrosis, phenylketonuria, and sickle cell disease.

In most states, babies get one newborn screening 24-48 hours after birth. Babies born in Texas and in a handful of other states, also get a second screening at 7-14 days old to provide another layer of detection. A few drops of blood are collected from the baby’s heel with a needle stick. The blood is then dabbed on filter paper and sent to the state lab for analysis. The results, which become available within a few days, can tell the experts in Pediatric Genetics and Metabolism at UT Southwestern whether your newborn is at risk for one of 55 screenable conditions.

Before newborn screening in Texas began in the 1960s, babies with serious metabolic or genetic conditions often didn’t get diagnosed until they developed irreversible physical or neurological symptoms. Expanded newborn screening began in Texas in 2006.

Today, newborn screening programs are considered one of the most important public health interventions.

Each state runs its own screening program and decides which conditions to include. This simple screening gives babies a chance to get lifesaving medication and nutrition therapies before devastating symptoms begin. Newborn screening also empowers families who face genetic conditions with knowledge to make informed decisions about their child’s care and their future reproductive plans.

Here are answers to some of the common questions we get about newborn screening and follow-up diagnostic testing.

Why does my baby need two heel sticks?

baby with eyes open
Babies in Texas are screened at birth and again a second time at 7-14 days old to provide another layer of detection.

Both screenings analyze the blood for signs of the same conditions. Some conditions are more detectable in the first few days after delivery, when a baby is metabolically stressed from birth. Other conditions are “disorders of intoxication,” which means that the levels of screenable components build up in the blood over time and may be more detectable in the second screening.

The first heel stick is done in the hospital as part of the regular course of newborn care. For the second screening, the baby will return to the hospital or their pediatrician’s office – your care provider will give you next steps. If you choose to have a home birth or deliver at a birthing center, your baby will still need the newborn screening – be sure to make a plan for when and where to get it done.

Which conditions are included in the screening?

There are currently 55 metabolic and genetic conditions included in the newborn heel stick in Texas. Screenable disorders are divided into six categories:

  • Amino acid disorders such as phenylketonuria (PKU), which was added in 1965 as one of the first screenable conditions in Texas. PKU stops the body from breaking down phenylalanine, so high levels build up in the blood and brain. A lifelong special diet and medications can manage PKU, preventing intellectual disability and developmental delay that used to be key features of this disorder when untreated.
Woman in hospital showing off newborn
Newborns in Texas are screened for 55 different conditions.
  • Fatty acid oxidation disorders such as MCAD deficiency, which was added in 2006. Babies with MCAD deficiency cannot break down certain fat into energy, which can cause low blood sugar, breathing problems, and loss of life that was frequently mistaken for sudden infant death syndrome. Frequent food intake can manage this disorder.
  • Organic acid disorders such as multiple carboxylase deficiency (MCD), added in 2006, in which the body cannot metabolize biotin correctly, resulting in seizures, brain swelling, and breathing problems. MCD is treated with biotin supplementation (a B vitamin).
  • Endocrine disorders such as congenital hypothyroidism, which was added in 1980. This is when the thyroid gland doesn’t make enough of its hormone. Thyroid hormone replacement therapy can prevent growth and intellectual development complications.
  • Hemoglobin disorders such as sickle cell disease, which was added in 1983. Sickle cell warps the shape of red blood cells, causing blocked arteries and pain crises that require frequent hospitalization. Multiple medication options or blood transfusions can be used to manage symptoms of sickle cell disease. A bone marrow (stem cell) transplant is a cure for some patients. A new single-infusion gene therapy , Zynteglo, was approved in 2024 for children with sickle cell disease.
  • Other significant disorders such as spinal muscular atrophy (SMA), which was added in Texas in 2021. SMA damages the nerve cells of the spinal cord and brain, causing difficulties with movement such as crawling, walking, or breathing independently. Multiple targeted therapy or gene therapy options for SMA have become available recently, which helped lead to the addition of this disease to newborn screening in every state within the last few years.
Newborn holding adult's finger

Screenings in your state

Each state decides which conditions to include in the newborn screening. You can learn more from your state’s health department. Baby’s First Test, a national newborn screening education resource center, also offers an online tool so you can look up which conditions get screened where you live.

Check your state

To be included in the newborn screening, a condition must meet the Recommended Uniform Screening Panel (RUSP) criteria:

  • There must be a specific and sensitive test available to detect it.
  • The health outcomes of the condition must be well-understood.
  • There is an available and effective treatment.
  • Identification of the condition could affect the family’s future reproductive decisions.

Meeting the RUSP criteria is key because flagging potential conditions without a treatment or change in outcome would cause unnecessary stress and pain for families. As new tests and treatments are developed, more conditions will be added to newborn screening.

Related reading: Unlocking language for babies who are deaf or hard of hearing

What happens if my baby screens positive for a condition?

Newborn screening is not a diagnostic test. While it can tell us whether a baby is at risk of a certain condition, additional testing may be needed to confirm a diagnosis. If a baby is flagged positive for a metabolic or genetic condition, the pediatrician receives the results and specialists are also contacted. A pediatric geneticist, genetic counselor, or other specialist may be involved to explain the results and discuss confirmatory testing and next steps.

Newborn screening has a high detection rate overall. However, there is a small chance of false-positive results for some conditions, which means a positive result was an error. In some cases, newborn screening can pick up whether a baby is a carrier of a genetic condition. That means the baby does not actually have the condition but they carry the gene variant, which could be inherited by their children one day.

How is a metabolic or genetic disorder diagnosed?

Dad kissing newborn
Pediatric geneticists and genetic counselors are available to explain the results with families.

There are generally two types of confirmatory testing. Biochemical testing of blood and/or urine will analyze the baby’s levels of enzymes, which are proteins that support metabolism, the necessary chemical reactions in the body or metabolites, which can be markers for certain disorders.

Genetic testing may also be used to analyze a blood or saliva sample for specific gene variants that can cause genetic conditions. Pediatric geneticists and genetic counselors are available to meet with families to discuss true and false-positive results, recommendations for further testing, and what a diagnosis might mean for the child’s health and possibly for their future siblings.

Together, we create an integrated care plan to support the baby’s development. The baby may need to see specialists such as a registered dietitian, a pediatric metabolic doctor, endocrinologist, hematologist, pulmonologist, or neurologist depending on what disorder the screen flagged as high risk. For many metabolic conditions, babies may need a special diet, eating schedule, or supplementation, along with medication. For other genetic conditions, medication and specialized therapies can help manage symptoms.

Do older kids need testing for new conditions added to the list?

The short answer is no. If your newborn does not flag positive for a screenable condition, it is unlikely that their older siblings have it. If your older children are healthy and haven’t shown symptoms of a condition, they likely do not need extra screening for conditions that were added to the list after they were born. Talk with their pediatrician if you have concerns about your older children’s health.

That said, most of the newborn screening conditions are recessive – if one child in the family has it, the other children are at increased risk. If your newborn screens positive and is diagnosed with a genetic condition, we may recommend genetic testing for older siblings.

Newborn screening is very important for a baby’s health and to inform future family reproductive decisions. Not every state offers two screenings – take advantage of this additional layer of reassurance if your baby is born in Texas.

To talk with an expert about newborn screening, call 214-645-3838 or request an appointment online.