Newborn blood spot screening: the ten conditions the NHS checks for

A healthcare professional, usually a community midwife or health visitor, pricks the baby's heel with a device holding a tiny needle and collects a few drops of blood on a special card. The test is quick and there are no known risks, although the baby may cry. Feeding, cuddling and keeping the baby warm help. The card is posted to a screening laboratory the same day, and samples are tracked by a fail-safe IT system that flags babies who have been missed or whose sample was delayed.

Information is given in pregnancy, usually at the first midwife appointment, and again after the birth, when the parents are asked whether they want the test. The screening programme is run by NHS England on recommendations of the UK National Screening Committee. Parents give verbal consent and can decline sickle cell disease, cystic fibrosis and congenital hypothyroidism separately, but the seven inherited metabolic diseases only as a group. A baby who has missed screening should be tested by speaking to the midwife, health visitor or GP.

The NHS screening leaflet gives approximate frequencies. About 1 in 2,800 babies born in the UK has sickle cell disease, an inherited blood disease affecting haemoglobin that brings painful attacks, serious infections and anaemia. Early treatment includes vaccinations and antibiotics to reduce severe illness. About 1 in 2,500 has cystic fibrosis, which affects digestion and the lungs, so babies may find it hard to gain weight and have frequent chest infections. Early treatment includes a high-energy diet, medicines and physiotherapy.

About 1 in 2,000 babies has congenital hypothyroidism, in which too little thyroid hormone is made. Untreated, babies do not grow properly and can develop permanent physical problems and learning disability. Treatment is daily thyroxine tablets, which allows normal development.

Screening can also find carriers of cystic fibrosis or sickle cell, which are explained in separate NHS information for parents.

The programme screens for seven inherited metabolic diseases (IMDs), in which the body cannot process certain substances in food. About 1 in 10,000 babies has PKU or MCADD, and the other conditions occur in 1 in 100,000 to 1 in 300,000 babies. Without treatment some can make a baby suddenly seriously ill. All are treated mainly by a carefully managed diet that differs for each condition and may include extra medicines.

Most babies have a no-conditions-suspected result. The NHS says you should get results by the time your baby is 6 weeks old, and the result may arrive by letter, phone or in person. If you have heard nothing by 6 weeks, contact your midwife, health visitor or GP.

Sometimes the test must be repeated, for reasons that do not necessarily mean anything is wrong, such as an unsuitable sample. Someone will contact you to explain and arrange a second test. A screen-positive result means a condition is suspected, not confirmed. Families of babies with a suspected metabolic condition are seen by a specialist metabolic team of doctor, dietitian and nurse specialist, and blood and urine tests confirm or exclude the diagnosis. Feeding continues normally while waiting, every 3 to 4 hours day and night in the case of several of the conditions.

Some results need faster action. For HT1 a baby is seen on the same day at a metabolic centre, with treatment starting before every diagnostic result is back. For MSUD, parents are told to take the baby immediately to the local hospital for admission, even if well, because untreated MSUD can lead to seizures and coma.

Tell the midwife or doctor as soon as possible if you or anyone else related to your baby has any of the conditions. The NHS programme asks about family history in pregnancy, and the metabolic team may write a care plan including an additional early blood spot sample, for example between 24 and 48 hours after birth for conditions such as IVA, HT1 and MCADD, and between 48 and 72 hours for PKU. This is in addition to the routine test.

Brothers and sisters who were never screened may also be at risk even without symptoms, and the metabolic team can arrange testing.

The test covers only these ten conditions. Many other inherited disorders, including Krabbe disease, the mucopolysaccharidoses and Smith-Lemli-Opitz syndrome, are not part of routine screening, and a baby with symptoms of any condition needs clinical assessment whatever the result was. The programme sometimes runs in-service evaluations in some areas, where consent is requested for extra conditions using the same heel prick sample.

Separately, research such as the Generation Study is sequencing the genomes of 100,000 newborns in the UK to test for around 200 treatable conditions, half of them inherited metabolic disorders. It is a research study, not routine screening.

Do not wait for screening results if a baby is unwell. Seek urgent medical help for poor feeding, excessive sleepiness, vomiting, floppiness, breathing difficulty, seizures, or yellow skin and eyes that persist. Call 111 for advice or 999 if the baby is very unwell.