Fifteen babies are dying every day in the UK from stillbirth, during labour or within four weeks of being born, according to a new report.

The health secretary Jeremy Hunt has pledged to halve the rate of such deaths by 2030, but the leading stillbirth charity, Sands, says the amount of funding committed is “woefully inadequate” - a charge the government rejects.

The new report is from MBRRACE-UK (Mothers and Babies: Reducing Risk through Audits and Confidential Enquiries Across the UK), which is a collaboration of academics and medical experts. It finds that there are big variations in death rates across the country from 4.1 to 7.1 per 1,000 births. Women from the poorest backgrounds and black and Asian mothers run a higher risk than others that their baby will die in the womb or soon after birth.

In nearly half of all stillbirths (46%), the causes of death are unknown, says the report. The biggest causes of death in the early weeks of life are complications following birth (32%) and congenital anomalies such as heart defects (28%), and very premature birth (13%).

The MBRRACE team flagged up the need for research into premature births and also called for every maternity unit to review and record the causes of death in the same way to try to discover why there are such stark variations around the country.

Sands says that a fall in the death rates will not happen without extra money. Maternity units are already struggling, without the staff to give high-risk women the extra scans they need, they say. Midwives are not getting sufficient training and some units do not have the funds for the monitoring equipment they need.

“It’s clear from today’s report that variations in care across the UK persist and the risk of your baby dying remains influenced by where you live and who you are,” said Judith Abela, acting chief executive. “While the secretary of state’s commitment to halving baby deaths in England by 2030 is encouraging – as is work elsewhere in the UK – the government’s financial commitment, which amounts to £3.60 per birth in England, is woefully inadequate.”

Bliss, the premature and sick baby charity, said there were significant staffing shortages in neonatal intensive care units and the report should be a wake-up call. “Over 90,000 babies born in the UK each year depend on neonatal care to survive and thrive – and that care depends on hospitals having the right numbers of nurses and doctors in place to meet quality standards”, said Caroline Davey, Bliss’s chief executive.

Dr David Richmond, president of the Royal College of Obstetricians and Gynaecologists, called for efforts to reduce pre-term births, which accounted for two-thirds of all stillbirths and deaths in the first weeks of life. The college is supporting the training of teams of doctors and midwives.

“Promotion of messages which may help women reduce the risk of stillbirth – such as maintaining a healthy weight prior to conception, stopping smoking and attending antenatal appointments – are also essential components to help end preventable stillbirths,” he said.

There was a slight fall in the overall stillbirth and neonatal death rate overall between 2013 and 2014, the report says. One of the report’s authors, Elizabeth Draper, professor of perinatal and paediatric epidemiology at the University of Leicester, said that in future they will measure any fall against the government’s target, set late last year, of halving deaths by 2030.

The government has so far invested £500,000 in a new improved process to review and learn from every stillbirth, £1m in improved training for staff, £2m in a new safety equipment fund which has been shared amongst 90 trusts and £365m on perinatal mental health.

“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,” said Ben Gummer, a health minister.

“We’ve committed to halve the number of stillbirths and neonatal deaths by 2030 - we are also investing in improved training for staff, new safety equipment and making sure hospitals review and learn from every tragic case.”

• This article was amended on 17 May 2016 to correct a figure. The report found that death rates across the country varied from 4.1 to 7.1 per 1,000 births; not 4.1 to 7.9.