"Standards not savings" are the reason for moving maternity and neonatal services from Withybush, health bosses said on Thursday.
During Hywel Dda University Health Board's public meeting last Thursday Paul Hawkins, chief operating officer, said that the changes involved an investment by the health board of £19m.
"There is no saving involved in this conversation," he said. "This is about delivery of standards."
Mr Hawkins added that the health board was "totally prepared" for services to move on August 4th.
"Staff recruitment has taken place and locum staff have been employed where posts have not been recruited to," he said. "This is a major piece of work for the health board."
He said that the dedicated ambulance vehicle (DAVE) had arrived and would be an "integral part of Withybush" staffed by two paramedics at all times. Other ambulances would also be employed if DAVE was already in use.
He added that Withybush's three bed midwife led unit will be open 24/7 and be run by a senior midwife according to the All Wales Midwifery Led Care guidelines. A community midwife would bring in labouring women and deliver the baby, ensuring continuity of care.
Executives added that the number of women who would use the DAVE were low.
"There is a very low number of women who will require transportation" said interim chief executive Karen Howell. "For the majority of women it won't come as a surprise to the woman or the service if they need transportation as it will be on their records."
Mr Hawkins added that the programme board will continue to meet weekly for two months after the August 4 implementation date.