Babies born outside normal working hours could be more likely to die, researchers have warned.
A study of more than 500 infant deaths found babies born outside the hours of 9am to 5pm, Monday to Friday, were more at risk - an extra one or two deaths per 10,000 live births.
The babies were significantly more likely to die from a lack of oxygen than those born during usual working hours, experts said.
They believe one possible reason for the extra risk is a lack of immediate access to senior staff at weekends and during the evenings. It comes after research published last month found patients were more likely to die if they were admitted to hospital at weekends.
A major report in June also said the NHS was "too reliant" on trainees outside of normal working hours and called on consultants to work more flexibly.
For the latest study, cases from Scotland were analysed but experts said there was no reason to believe the picture was not the same across the rest of the UK.
Gordon Smith, professor of obstetrics and gynaecology, and colleagues from the University of Cambridge analysed 539 neonatal deaths among more than a million births in Scotland between between 1985 and 2004.
The deaths occurred at birth or in the first four weeks of life and were not related to congenital abnormalities. All the births analysed were at or around full-term and were single births only, excluding twins or triplets.
The overall risk of death was 4.2 per 10,000 live births during the working week, rising to 5.6 per 10,000 at all other times.
Writing online in the British Medical Journal (BMJ), the experts said there could be several reasons for the findings.