British babies are more likely to die in their first month than those born in Latvia, Belarus and Cuba.
Researchers suggested reasons for this could include low breastfeeding rates, obesity and women delaying childbirth.
Figures from Unicef ranked the UK 30th out of 184 countries for lowest mortality rates within a month of birth.
Although comfortably within the top quarter, Britain lags behind countries from the former Eastern Bloc such as Latvia, Estonia and Belarus.
Researchers suggested reasons for this could include low breastfeeding rates, obesity and women delaying childbirth
Approximately 2.6 babies died in their first month for every 1,000 born in the UK in 2016. This is more than double the rate of Japan – which has the lowest neonatal mortality rate – and also higher than in Finland, Cyprus, Slovenia, Cuba, Greece and Portugal.
Experts cited several reasons babies are more likely to die in Britain, including mothers’ lifestyle and medical care.
Infants which are born to older or obese women have a greater risk of complications during birth and are also more likely to be premature.
In addition, twins and triplets – including those conceived through IVF – have higher mortality rates during pregnancy and shortly after birth.
Research has also shown that babies not breastfed straight after being born are more susceptible to fatal illnesses, possibly because mothers do not pass on their immunity.
Another reason could be that NHS staff are slower at detecting and treating infections, such as sepsis and pneumonia – two of the principal causes of neonatal deaths in Britain.
The report states that countries with low death rates tend to have ‘strong’ healthcare systems, ‘ample’ numbers of doctors and midwives, and high hygiene standards.
By contrast, many NHS maternity units are extremely understaffed and some have been found to be dirty.
The report said that, around the world, 2.6million babies die before they are a month old. Japan, Singapore and Iceland were found to be the safest countries, with Pakistan, Afghanistan and the Central African Republic the riskiest.
Henrietta Fore, of Unicef, said that although deaths of under-fives had halved over the past 25 years, ‘we have not made similar progress in ending deaths among children less than one month old’.
She added: ‘Given the majority of these deaths are preventable, clearly, we are failing the world’s poorest babies.’
Experts cited several reasons babies are more likely to die in Britain, including mothers’ lifestyle and medical care
Dr Clea Harmer, of Sands, the leading neonatal death charity, said: ‘The rate of babies dying in the first month of life in the UK has remained almost static for three years… we need more focus on delivering vulnerable babies in the right place with the right care.’
A Department of Health spokesman said: ‘We have committed to halving the rates of stillbirth, neonatal deaths and maternal deaths in the NHS by 2025. We’ve invested millions in staff training and safety equipment, as well as ensuring every unexplained stillbirth and neonatal death receives an independent investigation.’
Professor Neena Modi, of the Royal College of Paediatrics and Child Health, said: ‘The primary causes of newborn deaths in this global report – prematurity, complications around the time of birth, and infections – are also important causes in the UK.’