Editor’s note: This Unii Newborn article focuses specifically on the blood testing of newborns for genetic and metabolic disorders rather than more comprehensive newborn screening programmes.

Within the first few days of life, your newborn will have a blood test for a variety of genetic and metabolic disorders. This happens at about five days old (for nine different rare but serious disorders) at NHS hospitals. Newborn screening saves lives. When these conditions are detected and diagnosed early, appropriate interventions can prevent irreversible complications down the line.

While any tests performed on a baby so tiny sound scary, your baby’s sample will be taken simply, painlessly, and quickly. The hospital’s lab only needs a tiny amount of blood from the heel of one foot. This is then whisked away for an analysis known as the Guthrie test, the heel-prick test, or the newborn blood spot test.

Just considering the disorders that can be detected may also cause you a lot of worry at a vulnerable time. The list includes phenylketonuria, congenital hypothyroidism, galactosemia, sickle cell disease, and cystic fibrosis. Without prompt intervention, these disorders can cause serious health problems, including developmental delays, intellectual disability, organ damage, and even death. However, we do know that detecting any of these conditions early can make a significant difference.

A study published in the journal Archives of Disease in Childhood in 2007 estimated that newborn screening in the United Kingdom prevented around 1,400 deaths and avoided 3,000 years of disability annually. This study looked at the impact of newborn screening for just six conditions and found that early detection and treatment significantly reduced morbidity and mortality associated with these conditions. It's worth noting that this estimate is based on a specific set of conditions and probably does not capture the full impact of newborn screening in the UK. Further, the study is over a decade old, and updates in screening technology and expanded programmes may have led to even greater benefits in recent years.

In the United States alone, it is estimated that newborn screening has prevented more than 12,000 deaths and 20,000 cases of intellectual disability each year. Moreover, it has been estimated that every dollar spent on newborn screening in the same country saves at least $3 in future healthcare costs.

False-positive results can happen and cause unnecessary panic, as well as the need for additional testing and follow-up, which may make some parents of newborns even more concerned while their child is being tested. They may also have some ethical issues with screening generally. For example, screening tests used to identify carrier status for genetic disorders may offend their religious beliefs.

On balance, the benefits of newborn screening appear to far outweigh any potential risks. Beyond preventing serious health problems and even fatalities, it can arm parents with life-enhancing information about their baby’s health. This helps them make better decisions about healthcare overall.

As we cover in Unii’s Preconception Journey, some couples choose to undergo screening to identify whether or not they are carriers of any genetic diseases before trying for a baby. For example, Jnetics is a UK charity dedicated to preventing Jewish genetic disorders (JGDs) through education, screening, and support services. JGDs are inherited conditions that occur more frequently in the Jewish population because of shared ancestry and cultural practices.

What tests will my baby have at birth?

On Unii’s Newborn Journey, we explain the testing babies go through soon after birth.