Premature babies born in recent years are more likely to survive and less likely to have severe disabilities than those born in the mid-1990s, research has revealed.

According to the World Health Organisation, around 15 million babies worldwide are born before the 37th week of pregnancy every year, with premature babies at higher risk of severe disabilities, such as cerebral palsy, as well as a greater chance of delayed development of language and motor skills.

But experts say the new research offers good news, at least for children in developed countries.

“Not only has survival [of premature babies] improved, but survival without these [severe] disabilities,” said Pierre-Yves Ancel, professor of public health at the French National Institute of Health and Medical Research and co-author of the research.

The latest study sought to probe not only the later health of babies born extremely prematurely – below 26 weeks of gestation – but also those born on a less dramatic time-frame at 27-34 weeks, that have been studied less often.

“When you go up to the higher gestations you start to include more and more children that are born prematurely,” said Andrei Morgan, another author of the research.

Published in the British Medical Journal by a team from a number of French institutions, the research drew on the results of a study known as Epipage 2. This study collected data from across France for babies born between 22 and 34 weeks of gestation during 2011 –with a total of 5,567 live births noted.

Based on medical questionnaires from 3,599 of the children assessed at around two years old (an age relating to their due data, rather than their birth date) the results reveal that 6.9% of children born at 24-26 weeks had cerebral palsy. The figure fell to 4.3% for those born at 27-31 weeks and to 1% for those born at 32-34 weeks. Fewer than 1% of the children overall were found to have severe visual impairments or hearing difficulties.

The medical data was also compared to that collected in the original Epipage study, which tracked the outcomes for premature babies born at 22-34 weeks in nine regions of France during 1997.

The results reveal that since 1997, survival for babies born at 22-31 weeks has increased by 6%, while survival without sensory or neuromotor disabilities increased by just over 7%. No change was seen for less premature babies, with survival – and survival without severe disabilities – high in both studies. More specifically the rate of cerebral palsy among toddlers declined by 3.3% both for those born at 24-31 as well as those born at 32-34 weeks.

“It is not clear what causes cerebral palsy - it is probably a combination of factors,” said Morgan, adding that advances in the care of pregnant women, women in labour and newborns are all likely to have contributed to the improved rates, with improvements in screening for various conditions also likely to have increased the rates of survival without severe disabilities.

The latest study also asked parents to complete a questionnaire probing various areas of neurodevelopment, including their toddler’s communication abilities and motor skills.

The results from 2,506 children without severe disabilities reveal that just over half of children born at 24-26 weeks were found to have scores markedly below average. Those who spent longer in the womb fared better, with just under 41% and just over 36% of children born at 27-31 weeks and 32-34 weeks respectively falling below the threshold.

That, says Ancel, suggests that while the rates of severe disabilities among premature babies is improving, they remain at risk of developmental delay.

Andrew Shennan, clinical director of Tommy’s Prematurity Research Centre in the UK, agreed that the research showed those born preterm were still at risk of delayed development, but added there was good news.

“This data suggests that improvements in care to mother and baby are now having a beneficial impact in terms of survival,” he said.

Dieter Wolke, professor of developmental psychology and individual differences at the University of Warwick who was not involved in the study, agreed, adding that the positive findings mirrored those of other large studies.

But, he said, it was of concern that babies born very preterm were at risk of developmental delay.

“With higher survival of preterm children but no improvement in neurodevelopmental outcome, there will be overall more children with neurodevelopmental problems in the community,” he said, adding that many problems are linked to cognitive and social skills.

“More emphasis should be put in follow-up programmes on social and communications skills and include experts in these fields, [such as] psychologists [and] speech therapists, to suggest appropriate interventions,” he said.

• This article was amended on 17 August 2017. An earlier version referred to Dieter Wolke as saying it was of concern that babies born very preterm have no better outlook for their neurodevelopment than those born more than a decade before. This has been amended to say that his concern was that that babies born very preterm were at risk of developmental delay. The current study did not directly compare neurodevelopment of children between two cohorts.