Only two out of the 165 maternity units had a consultant present round the clock, according to the Royal College of Obstetricians and Gynaecologists.
A survey of 165 maternity units found that in 2014/2015 around 27% of labour wards have consultants physically present overnight on weekdays, falling to 15% at the weekend.
‘Almost half of hospitals lack senior specialist at weekends and three in four labour wards have no consultants overnight.’
The census by the Royal College of Obstetricians and Gynaecologists (RCOG) also found the number of consultants may have reduced since figures were first recorded in 2013 and some recommendations on early pregnancy care had not been implemented.
Edward Morris, vice-president of clinical quality at the body, said: "The RCOG recommends that trusts should ensure the adequate provision of consultant cover to deliver high quality safe care to women.
It is important to highlight that all consultant-led maternity units currently have 24-hour access to consultant obstetricians on call, some with resident working where needed."
"Ultimately, local trusts need to look carefully at the mix of their patient load, risk profile and staffing to decide whether their particular unit needs more frequent consultant presence."
The number of consultants had reduced since the survey was first carried out, however the body said this was likely to be a reflection of a fall in responses.
However it found recommendations to increase the low number of weekend early pregnancy services had not been put into effect.
"It is not clear why this remains the case as in the interest of patient care, this would be considered one of the first services that could be provided seven days a week," the RCOG said.
"Researchers at Oxford University have shown that overnight consultant obstetrician presence isn't proven to improve care, and a national diktat to that effect would mean the closure of many smaller units, which is another reason why it wouldn't necessarily be a good idea."