About newborn bloodspot screening - What are newborn babies screened for?
In Wales all babies are offered screening for the following conditions:
Inherited metabolic disorders
Babies with these rare inherited disorders cannot process certain substances in their food. Without treatment, babies with these disorders will have serious long-term health problems and for some of the disorders babies can become suddenly and seriously ill.
Newborn screening means that babies who have one of these disorders can be identified early and have the right diet and treatment and specialist care to prevent health problems from developing.
It is very important to let your healthcare professional know if you have a family history of any of these metabolic disorders.
Babies are offered screening for the following six inherited metabolic disorders (IMDs):
- Medium-chain acyl-CoA dehydrogenase deficiency (MCADD)
- Phenylketonuria (PKU)
- Congenital hypothyroidism (CHT)
- Cystic fibrosis (CF)
Medium-chain acyl-CoA dehydrogenase deficiency (MCADD)
Babies with MCADD have problems breaking down fats to make energy for their body. If babies are not screened and have this disorder, the diagnosis may only be made when they become suddenly and seriously unwell. Three or four babies in Wales are born with MCADD each year.
Phenylketonuria (PKU)
Babies with PKU cannot break down an amino acid called phenylalanine. Amino acids are ‘building blocks’ of protein and we get protein from certain foods. If untreated, babies with PKU will develop a serious permanent mental disability. Newborn screening means that babies can be identified and treated with a special diet to prevent this disability.
Three or four babies in Wales are born with PKU each year.
Maple syrup urine disease (MSUD), Isovaleric acidaemia (IVA), Glutaric aciduria type 1 (GA1) and Homocystinuria (HCU)
Babies with MSUD, IVA, GA1 or HCU cannot break down certain amino acids that are contained in the protein we eat, in the usual way. This leads to harmful levels of certain amino acids and other harmful chemicals in the blood. These are rare disorders and it is expected that one or two babies in Wales will be born with one of these disorders each year.
Congenital hypothyroidism (CHT)
Babies with congenital hypothyroidism do not have enough of the hormone thyroxine. Without this hormone, they do not grow properly and can develop a serious, permanent, physical and mental disability.
Approximately 18 babies in Wales are born with CHT each year.
Newborn bloodspot screening means that babies with CHT can be identified and treated early with thyroxine tablets. This treatment will prevent serious disability and allow the baby to develop normally. If babies are not screened and are later found to have CHT, it may be too late to prevent them becoming seriously disabled.
Cystic fibrosis (CF)
This inherited condition affects digestion and the ability of the lungs to work properly. Babies with CF have problems digesting food and may not gain weight well. They are also more likely to have frequent chest infections.
Between 12 and 14 babies in Wales are born with CF each year.
Newborn bloodspot screening means that babies with CF can be identified and treated early with a high-energy diet, medicines and physiotherapy. Early treatment is thought to help children with CF live longer, healthier lives. If babies are not screened for CF and they do have the condition, they can be tested later, but parents may have an anxious and uncertain time before CF is diagnosed.
Sickle cell disorders (SCD)
These are inherited disorders that affect the red blood cells. If a baby has a sickle cell disorder, their red blood cells can change to a sickle shape and become stuck in the small blood vessels. This causes pain and damage to the baby’s body, serious infection, or even death.
Three or four babies in Wales are born with a sickle cell disorder each year.
Newborn bloodspot screening means that babies with SCD can be identified, and receive early treatment, including immunisations and antibiotics. This, along with information and support for parents, will help prevent serious illness and allow the child to live a longer and healthier life.
Page last reviewed: 25th February 2025