UK babies are missing out on checks for rare but serious health conditions, putting lives at risk, according to a report from the charity Genetic Alliance UK.
The NHS offers newborns a blood test to screen for up to nine conditions.
Many other European countries look for 20 or more illnesses and the US screens for more than 50, the charity says.
The UK National Screening Committee says its recommendations are based on evidence and are regularly reviewed.
It is up to the governments in England, Scotland, Wales and Northern Ireland to decide which tests to provide.
Genetic Alliance UK says affordable ways to expand the screening exist, but are not being used.
What is newborn screening?
The newborn heel prick or blood spot test involves taking a small sample of your baby's blood for screening, usually during the first week after birth.
It is not compulsory but it is recommended because it lets doctors identify rare illnesses early so the best treatment can be offered to prevent disability and, in some cases, even death.
Genetic Alliance UK says heel prick blood samples could be used to detect more conditions than those for which screening currently happens.
It says the UK is lagging behind other countries and some treatable illnesses are going undetected.
It also means couples are unable to make an informed decision about whether to have more children who might also be at high risk of these rare, inherited illnesses, the charity adds.
Sara Hunt, from East Dulwich, is the mother of two boys, Alex and Ayden. Both were born with a rare condition called ALD or adrenoleukodystrophy, but getting a diagnosis was a struggle.
ALD is not routinely checked for in the UK as part of the newborn heel prick or blood spot test screening programme, but is in some other countries.
It is an X-linked recessive genetic disorder, which means that only boys are affected and the mother may be a healthy carrier of the disease.
Alex, Sara's eldest, was not diagnosed until he was seven. By that time his condition was already advanced. The disease was attacking his brain and nerves.
He died 12 years later at the age of 19. His younger brother, Ayden, was diagnosed early enough to be closely monitored and have treatment. He is now 19 and healthy.
Sara, who has since set up a charity in Alex's name, said: "It's just heartbreaking to keep seeing boys that could have been identified and treated if they had been offered a test to diagnose their condition as a baby.
"Other countries offer it so I don't see why the UK can't too."