Statistics published by the regulator show that there was a 1.6 per cent fall in the number of childminders between 31 December 2015 and 31 March 2016.
This equates to a loss of 770 childminders, bringing the total to 46,287. The fall in registered childminders follows a 1.8 per cent decline between August and December last year, when the number of registered childminders fell by 879 over the three-month period to 47,057.
The total decline in numbers of childminder places since August 2012 now stands at 23,000. The figures have prompted concerns about how demand for childcare will be met when free childcare entitlement is extended to 30 hours a week next September.
Neil Leitch, chief executive of the Pre-school Learning Alliance, said it is "very concerning" that childminder numbers have continued to decline.
"The government has made it clear that it expects childminders to provide the solution to the problem of limited nursery and pre-school capacity when the 30-hour free entitlement offer rolls out next year," he said.
"But when the number of childminder places has dropped by nearly 23,000 in less than four years, we simply cannot see how this is possible.
"The DfE has rightly identified childminders as a vital source of flexible early years provision, and yet has done little to tackle this continuing trend.
"Government must do more to identify and tackle the reasons for this trend. Failure to do so could place even greater pressure on a 30-hour policy that is already on shaky ground."
In a consultation document published by the Department for Education in April this year, the department stated that childminders would play a key role in delivering flexible provision when the 30 hours is implemented.
However, research by the Pre-school Learning Alliance earlier this year found that half of providers don't have the capacity to meet demand for the 30 hours.
Earlier this month the Professional Association for Childcare and Early Years warned the government that it was being too optimistic about the role childminders will play in the expansion of free childcare.