Women should get IVF treatment without having to fulfil a legal requirement that the child has a father figure, says the UK's fertility regulator.
Man not needed? The law demands a father figure for IVF children
Suzi Leather, chairman of the Human Fertilisation and Embryology Authority, says that the clause is "nonsense".
She claims that it discriminates against single and lesbian women - and out of step with "changes in society."
But Jack O'Sullivan, of Fathers Direct, said studies showed the benefits of the presence of a male figure.
At present, doctors are required to take account of the "need of the child for a father" prior to allowing women to go ahead with fertility treatment.
The HFEA is planning a major review of this and other child welfare "conditions" placed on would-be parents.
It is calling for an update of the 1990 Human Fertilisation and Embryology Act, which is perceived as "outdated" on several fronts.
In a speech to the authority's annual conference on Wednesday, Ms Leather set out how she thinks such clauses should be brought into line to tally with modern society.
She said: "It is absolutely clear if you think about the changes in society and the different ways that families can be constituted that it is anachronistic for the law to include the statement about a child's need for a father.
"It seems to me a bit of nonsense to have that still in the legislation."
She said that one in four families was now headed by a single parent - and that the government had moved to recognise gay marriages.
She said it was more important to assess women on their medical and social circumstances than the exact arrangement of their relationships.
"I don't think single and lesbian women should be excluded on those grounds," she said.
Some clinics do currently offer fertility treatment to lesbian women - although to fulfil the letter of the law, the women have to show that some form of father figure, such as an uncle or grandparent, will be available to the child.
But Ms Leather warned the current legislation might push some women to seek sperm on the internet.
She said: "That is a dangerous thing that carries greater risks both for the women involved and indeed is a disadvantage for the children created."
Liberal Democrat MP Evan Harris agreed with the proposed change.
He said: "This would be a welcome step, since the evidence is now absolutely clear that children brought up by lesbian couples develop normally and just as well adjusted as children brought up by mixed gender parents.
"Also, single women can do a perfectly satisfactory job on raising children especially when compared to two-parent families with the same income.
"There is, therefore, no longer any reasonable basis for a legal requirement that consideration of the welfare of the child should specifically refer to the need for a father" .
Jack O'Sullivan, whose Fathers Direct group campaigns for the rights of fathers, said that while discrimination against single and lesbian women was wrong, the benefits of a father figure were proven by scientific studies.
He said: "Fathers matter and it would be a mistake to downgrade that important role."
A spokesman for the charity Life said: "Suzi Leather's comments that a child's need for a father is somehow outdated is a slap in the face for all men who have campaigned for so long in favour of equal recognition for the vital role that the father plays in the upbringing of a child."
The group Comment on Reproductive Ethics issued a statement calling Ms Leather's comments "political correctness at its most absurd".