The energy minister insisted that she did not want motherhood to play a part in the campaign and “deeply regret that anyone has got the impression that I think otherwise”.
Mrs Leadsom said she had felt “under attack” since the row over her comments, which were branded “vile” by one senior Tory MP while a fellow minister said it showed she was unsuitable for Number 10.
In an interview with The Times, Mrs Leadsom said: “Genuinely I feel that being a mum means you have a very real stake in the future of our country, a tangible stake.”
The Home Secretary has previously spoken about how she and husband Philip were affected by being unable to have children.
Mrs Leadsom told the Daily Telegraph she believed that having children has “no bearing on the ability to be PM”.
“I absolutely said, what I specifically said, is that motherhood should not play a part in the campaign,” she said.
“I was pressed to say how my children had formed my views. I didn’t want it to be used as an issue. Having children has no bearing on the ability to be PM. I deeply regret that anyone has got the impression that I think otherwise.”
Asked if she would apologise to Mrs May she said: “I’ve already said to Theresa how very sorry I am for any hurt I have caused and how that article said completely the opposite of what I said and believe.”
Mrs Leadsom said she felt “under attack, under enormous pressure. It has been shattering”.
In the wake of her Times interview, business minister Anna Soubry said Mrs Leadsom’s comments meant she was “not PM material” while Scottish Tory leader Ruth Davidson said there was a “gulf in class” between the two candidates and senior MP Sir Alan Duncan said the energy minister’s remarks were “vile”.
But Mrs Leadsom’s key supporter Iain Duncan Smith, the former Tory leader, claimed she is facing a “black-ops” campaign by MPs who want to “denigrate her reputation”.