The two birthing pools at Watford General Hospital have been temporarily taken out of service for "unplanned but necessary" works.
The pools were closed on Tuesday, July 8, for changes to be made to the pipes that supply water to them.
Tracey Carter, chief nurse, said: "We always strive to give women as much choice around their birth plans and maternity care as we can.
"However, unplanned but necessary works to our two birthing pools at Watford Hospital mean a small number of women are temporarily unable to have a water birth as a choice.
"Our midwives have talked privately to the women affected and have outlined other options available.
"We aim to re-open both pools very shortly, after a technical reassessment on Monday of next week."
Of the 500 women on average who give birth at the hospital every month, in April of this year 25 women used the birthing pools and in May 21 women used the birthing pools.