The NHS trust that runs a birth centre at Pontefract Hospital said staff sickness was the reason it had been closed on several occasions over the past month.
Last month the Mid Yorkshire Hospitals NHS Trust said the centre would not be permanently closed after the birth facility shut its doors without warning.
But a staff member, who did not want to be named, told the Express the centre had only been open "on eight to 10" occasions over the previous six weeks.
They said the closures were not announced to patients and midwives with prior warning, and staff were often unclear where they would be working.
They said: "It is being made unsafe for women. Someone could end up giving birth in a car park if they turn up and the centre is closed.
"Women are forced to go to Pinderfields Hospital or even Dewsbury at short notice.
"It is not acceptable to remove that choice for patients."
Yvonne Rowlan, assistant director of nursing and midwifery, at the Mid Yorkshire Hospitals NHS Trust said: “Our priority is to maintain a safe service that offers choice to women.
"Friarwood Birth Centre has closed on a number of occasions in the last month due to staff sickness, which is causing difficulties in maintaining the staffing in all three of our birthing centres.
"We only ever take a decision to close if we feel it would compromise the safety of pregnant ladies and their babies to remain open.
"If any women are uncertain about arrangements they should continue with the normal process of calling the triage team before they set out on 01924 543002/543003.
“Despite these challenges, as a busy trust we are proud of the fact that we have the full range of birthing options to offer local women − from home births and maternity-led units to consultant-led hospital births − and in the last year our maternity service has safely delivered over 6,000 babies.”