A fertility consultant has warned that changes to NHS-funded IVF treatment in Wales could lead to failed attempts and longer short-term waiting times.
Free IVF will now only be provided by NHS organisations, under assembly government rules.
Peter Bowen-Simpkins, of the private London Women's Clinic Swansea, says NHS units will "struggle to cope".
But Health Minister Edwina Hart has said that standards and current waiting times will not be adversely affected.
The Swansea clinic at Singleton Hospital has lost its NHS contract under the One Wales coalition agreement between Labour and Plaid Cymru after the last assembly election.
Patients living in a catchment area from Bridgend to Aberystwyth are to be catered for at a new NHS clinic that has just been set up at Neath Port Talbot Hospital.
London Women's Clinic medical director Mr Bowen-Simpkins expressed concerns that the new unit would not be able to cope and patients could instead be sent to the NHS clinic in Cardiff.
He told BBC Wales: "The last few years we have been taking patients from Cardiff because of the overflow and this unit in Neath will take a while to set up and become fully operational with good success rates.
"Whenever you start a new unit, success rates are poor because the unit is setting up and people are getting used to new equipment.
"They will do this at the cost of at least £1m and buy in new equipment when they are already £40m in debt - it's a complete waste of money.
"I am not speaking out because of the financial impact on us as we make very little profit from NHS cycles - I am speaking out as a clinician."
The changes came into force on 1 April but the Swansea clinic still has some 220 NHS patients waiting for results on their second free cycle.
One cycle of IVF treatment normally takes four to six weeks to complete.
Patients with fertility problems were given the right to a second course of treatment in Wales from April 2010.
In the five years before that, women were given one cycle of IVF treatment free on the NHS.
Susan Seenan of the patient charity Infertility Network UK said: "It is extremely important that patients who need fertility treatment are referred and treated as quickly as possible as any lengthy delays could have an adverse effect on success rates, as well as the emotional impact of long waiting times on couples.
"We have already called for additional staffing and other NHS resources to be provided before any changes are made as it would be totally unfair for patients to have their chances of success affected by a lack of resources at Cardiff when there is additional capacity in Swansea."
Health Minister Edwina Hart has said that health boards were working with the Welsh Health Specialised Services Committee (WHSSC) to replace private provision.
In an answer given to Nick Bourne, the leader of the Conservatives in the assembly, in February, she said: "The transition to an NHS service is planned to ensure that service standards and current waiting times are not adversely affected.
"WHSSC's priority is to ensure that patients' clinical continuity is not compromised and patients who have already been seen by the private provider will be able to complete their cycle of treatment."
The WHSSC said new patients had been seen in Neath since 1 April.
"Patients who have already had a consultation at the London Women's Clinic or those who have had a first cycle and are eligible for a second will continue to be treated at the London Women's Clinic.
"This is to ensure that continuity of care is maintained for patients.
"WHSSC are working with the London Women's Clinic to ensure that patients will not be disadvantaged as a result of the change in provider."
The four main political parties in the assembly have been asked to respond, and below are the replies received so far.
Conservatives said: "IVF treatment in Wales should not become a postcode lottery under any circumstances."
The party said it would spend "appropriately based on patient need - not ideological warfare - and in this case, make sure that couples seeking IVF treatment in west Wales are not ignored or deprived."
Veronica German, Welsh Liberal Democrat health spokeswoman, said: "Labour-Plaid political dogma is resulting in people travelling longer and reducing their services.
"Stopping NHS funding to the Swansea centre will mean that services in Cardiff will be stretched with longer waiting lists and this could have a detrimental effect on the fertility cycles of patients."