Some hospitals are failing to investigate the deaths of stillborn babies or those who die in the first month of life, according to a new report.
Experts behind MBRRACE-UK - a major study into Britain's high stillbirth rate - said some hospitals carry out "cursory" investigations into whether lessons can be learned about the care of mothers and babies, while others fail to record data.
The overall stillbirth and neonatal death rate has been found to have fallen slightly.
However the team found many parts of the UK still have death rates that are too high. The experts said these hospitals should carry out thorough reviews of each case.
The following networks were found to have rates that are more than 10% higher than the UK average:
Lancashire and south Cumbria
Yorkshire and the Humber
Southern West Midlands
Black Country and Trent
Overall, death rates varied across the UK, from 4.9 deaths to 7.1 per 1,000 births. This variation cannot solely be explained by factors such as poverty, mother's age, multiple birth and ethnicity, the experts said.
Some NHS trusts also had poor levels of completed data for key areas such as antenatal care, the experts found, while there were also wide variations in how some deaths were recorded, such as for heart defects.
David Field, professor of neonatal medicine at the University of Leicester, and one of the authors of the report said some hospitals investigate "in fantastic detail" whileothers fail to carry out proper investigations
He said trusts needed to be "hyper-critical" to see whether things could have been done better, adding: "You can't just say all the deaths are inevitable".
While in many cases, babies might not have been able to be saved, he said "you want to know about those deaths where things might have been done differently".
stillbirths and deaths in the first 28 days of life in 2014
stillbirths and deaths in the first 28 days of life in 2013
The stillbirth rate and death rate in the first month of life is now 5.9 deaths per 1,000 births in the UK, which is still "significantly higher than rates reported in other high-income European countries", the report said.
Almost 50% of stillbirths and just over 5% of deaths in the first month are classed as having an unknown cause.
More than 90% of families were offered a post-mortem to help establish what happened but even this varied according to the hospital.
In 45% of trusts and health boards this offer was made for all deaths, but 22% of organisations offered a post-mortem for less than 90% of deaths.
Overall, parents consented to a post-mortem around 40% of the time.
Professor Neena Modi, president of the Royal College of Paediatrics and Child Health, said the report highlighted further evidence "of the poor quality of much administrative data in the NHS and the lack of consistency across the UK in reporting the causes of stillbirths.
"Without high quality data it will continue to be very hard to build up a nationwide picture of the reasons for perinatal losses, or improve many other aspects of pregnancy and newborn care."
It is positive that progress has been made, but this important report is further evidence that we must continue to tackle variation to help ensure far fewer families go through the heartache of losing a child.