Screening for Birth Defects

While some disorders, like Down syndrome, are visible at birth, others show NO outward signs. How do doctors find these seemingly invisible birth defects? Within 48 hours of a newborn’s birth, the baby will be screened for a host of detrimental or potentially fatal disorders. To perform a hearing screen, a doctor first checks the baby’s hearing using a small, soft earphone or microphone. Although hearing impairment only affects about 3 in 1,000 babies, this test is vital, because infants with UNTREATED hearing problems often experience delayed language development. The second part of a newborn screen involves collecting a drop of blood from the baby’s heel. That tiny blood sample will be tested for anywhere from 10 to 50 defects. How rigorous this testing will be depends on WHERE the child was born. Every U.S. state has different laws regarding newborn screening. But some tests, like the one for phenylketonuria [Say: fen-l-kee-toh-noo r-ee-uh] or PKU, are performed all over the country. Babies with PKU cannot process a component of protein called phenylalanine [Say: fen-l-al-uh-neen], which is found in most foods. Without treatment, phenylalanine builds up in the blood, causing brain damage and mental retardation. Luckily, putting a child on a low-phenylalanine formula can offset these PKU effects. Another nationwide newborn screening looks for a disorder called congenital hypothyroidism. Infants with this disorder do not have sufficient stores of the thyroid hormone and will experience delayed growth and brain development if they are NOT treated with oral thyroid hormones. Congenital hypothyroidism affects up to one in 4,000 babies and is one of the most common disorders detected during newborn screenings. A third imperative screening detects galactosemia, a disorder that can cause mental retardation, blindness, and death in infancy. Galactosemia occurs when a baby can’t convert a milk sugar called galactose into a useable sugar called glucose. Treatment for galactosemia involves eliminating all dairy products from a baby’s diet. Finally, all U.S. states test for sickle cell disease, an inherited blood disorder that causes red blood cells to mutate. These mutated cells can lead to anemia, severe bouts of pain, damage to internal organs, and even death. Although there is no treatment for sickle cell, vigilant medical care can help reduce these complications. And while there are a number of additional disorders that an initial blood test can detect remember that a doctor will NOT need to screen for obvious problems, like Down syndrome, spina bifida, and dwarfism. If you have questions about your baby’s newborn birth defect screening, talk to your doctor before you leave the hospital. And try not to worry too much. The March of Dimes suggests that very few newborns are actually diagnosed with a problem following their screenings!