Some NHS staff say they are struggling to find childcare for young children due to nursery closures as a result of the coronavirus outbreak.
One nursery owner said there was little incentive for some to stay open due to the costs of paying staff to look after only a handful of children.
Nurseries are only allowed to provide childcare for children of key workers and vulnerable children.
Ministers said they were working with councils to find enough places.
Schools are providing care for older children of essential staff, such as those who work in the NHS and care sector.
But nurseries and other childcare providers usually look after younger children and babies.
'There's been a bit of a postcode lottery with regards to nurseries'
Dr Owain James, a GP from Bridgend, has struggled to find provision for his two-year-old after both the childcare providers his family usually use closed.
It followed the government announcement they could only stay open to care for the children of essential workers during the pandemic.
The family also have a three-year-old who has a place in a school.
They found a third nursery but found out over the weekend it was also shutting - meaning Dr James has had to cancel locum shifts this week.
"People look at medicine as a vocation rather than a job.
"Both of us are doctors and we've got to look after the kids first and foremost," he said.
"But we were hoping that we would be able to throw ourselves into work, make ourselves readily available and to put our hands up really to say we want to do what we can do, but unfortunately it's not going to turn out that way."
He says there is a "mixed bag" of experiences amongst colleagues with "the issue being the pre-school age".
"I think there's been a bit of a postcode lottery with regards to nurseries," he said.
Dr James added it could hit healthcare workers "morale and their ability to work".
The Mill Child Care Centre in Denbighshire has 118 children on its books but is only providing care for 11 while the restrictions are in place.
Owner Ffion Roberts says the last week and a half had been "a major rollercoaster".
She has remained open with five staff members and another 19 have been placed on the UK government scheme which pays 80% of their wages.
A Welsh Government scheme paying grants of £10,000 to all childcare providers, with a rateable value of up to £100,000, is a great help with overheads, she said.
But across Denbighshire, by last Friday 87 of its 125 childcare settings had closed.
"I have no fees coming in except for the fees of the 11 children who are coming here," said Mrs Roberts.
"But that doesn't go anywhere near paying the five members of staff that have bravely come in."
She said supporting NHS staff was an important reason to stay open but she had to look "very, very carefully at the balance sheet".
"If the balance sheet doesn't balance, when all of this is over we won't be here and there'll be a desert of childcare provision for the threes and under."
The Welsh Government said there were gaps in the UK government's interventions and it would announce a cross-sector coronavirus fund to respond to the specific needs of businesses, which would help meet fixed costs which are no longer covered by earned income.
"We are working with local authorities to identify sufficient childcare for 0-4 year olds in settings across Wales for vulnerable children and the children of critical workers," said a spokesperson.
More than 700 schools have stayed open to look after the children of NHS staff, carers and other key workers.