A care package aimed at reducing the risk of babies being stillborn may offer marginal benefit, research suggests.
Findings from a major study were inconclusive, but experts stress that advice for pregnant women remains the same.
Women who notice a change in their baby's movements in the womb should seek advice from their midwife or local maternity unit immediately.
Previous research had suggested that encouraging women to pay attention to their babies' movements, combined with additional checks and early delivery of babies at risk, might help cut rates of stillbirth by 30 per cent.
Researchers led by the University of Edinburgh investigated whether a similar care package could help to reduce rates of stillbirths in a large randomised controlled trial.
The study - called AFFIRM - analysed outcomes from more than 400,000 pregnancies from 33 hospitals around the UK and Ireland.
It is the largest study of fetal movement awareness to date and the first in the world to investigate fetal movement combined with an intervention designed to reduce stillbirth.
Results indicated a marginal drop in the stillbirth rate, from 44 in 10,000 births after standard care to around 41 in 10,000 births with the intervention.
Further analysis suggested the intervention might prevent five stillbirths for every 10,000 babies born. The effects were too small to prove that the care package had been beneficial, however. The team say further research will be needed.
Study lead Professor Jane Norman, Director of the Edinburgh Tommy's Centre at the University of Edinburgh, said: "The study was designed to detect an effect of 30 per cent or greater. The results suggest that if there is a beneficial effect, it is much smaller than this. It is not possible to say with certainty that the intervention has any effect on reducing rates of stillbirth.
"The research adds further evidence to suggest that being aware of baby movements may help to marginally reduce risks of stillbirth, but it is unlikely that this strategy alone will be reliable for monitoring the wellbeing of babies in the womb. Other interventions will likely be needed to reduce stillbirth rates worldwide."
In the group that received the care package, more women were induced early and there were higher rates of caesarean section deliveries, the study found.
Researchers say an economic analysis of these data will help policy makers assess whether this approach might fit into a stillbirth reduction strategy.
Professor Alexander Heazell, co-investigator on the study and Director of the Tommy's Stillbirth Research Centre at the University of Manchester, said: "There are a number of other ongoing fetal movement awareness studies. Results from the AFFIRM trial should be analysed in conjunction with those studies before recommendations can be made on wider implementation of this approach."
An estimated 2.6 million babies are stillborn each year around the world. In the UK, around one in 200 pregnancies end in stillbirth, around nine babies every day.
Up to a half of women whose pregnancy ends in stillbirth report reduced movements of their babies in the womb in the previous week.
Jane Brewin, Chief Executive of Tommy's, said: "We know that reduced baby movements is associated with the placenta not working so well and the baby's health being compromised. The advice for mums-to-be remains the same - if your baby's movements change please consult your midwife or local maternity unit immediately."
The study, published in The Lancet, was initiated and funded by the Scottish Government's Chief Scientist Office. It was also funded by Tommy's, the baby charity, and Sands, the Stillbirth and Neonatal Death Charity.
Dr Clea Harmer, Chief Executive at Sands (the Stillbirth And Neonatal Death charity), said: "Women's awareness of their baby's movements remains a key part of public health information during pregnancy. At least one in three of the parents Sands supports tells us that their baby's movements had slowed down or changed in the womb before they died. Getting the message out that women need to report any concerns straightaway remains vital to routine antenatal care."