Personally, I never thought that she did mean it as a nasty personal jibe.
As is often the case, context is useful:
“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.”
On the other hand, the knee-jerk reaction of accusing a serious journalist of engaging in "gutter journalism" was perhaps not the wisest of post-blunder courses of action.
Eric Pickles, the former cabinet minister who is supporting May’s bid [commented] “I don’t like to see those kind of reactions in a potential prime minister because she is going to have to deal with a lot more [and] tougher people than that particular journalist, Rachel Sylvester. I think Mr Putin might be just a little bit more difficult.”
I can understand that she doesn't have much experience in dealing with the media, but it looks like she'll need to face a rather steep learning curve.
Andrea Leadsom apologises to Theresa May for motherhood remarks
Tory leadership candidate says sorry to her rival, Theresa May, after ‘fluffing her first major interview with a very serious journalist’
http://www.theguardian.com/politics/2016/jul/10/andrea-leadsom-apologises-for-motherhood-remarks