The article makes a valid point in that bringing a pregnant woman to a charity event in support of parents who have lost children can be seen as tactless - especially if said parents have suffered miscarrages, stillborns, or the loss of infants.
What it doesn't take into consideration, however is the fact that this is not the first event for this charity that William and Catherine have attended together, and Child Bereavement UK places emphasis on William's patronage of the organization - he gets his own link in the charity's "About Us" section and is the first patron listed on their patron page (above even the organization's founder). Given that the organization works with a large number of people it's not all that difficult to believe that they took the time to select parents who had lost older children and not infants and who were able to be around a pregnant woman - as the article sarcastically points out, we're not told who any of the people they met had lost (or the circumstances under which), or their full names. Although, in all honesty, why would you expect the people who are a part of a charity that deals with such delicate and personal matters to reveal said matters to the press?
I have a couple favourite parts about this article, though. First of all, I love how Whalen keeps on referring to the Bates Motel, as if this is something out of a Hitchcock movie. I kind of suspect that either she hasn't seen Psycho or A&E is paying her for using the name a lot and thus advertising their new TV series. I also kind of find it funny that Whalen criticizes William for mentioning that he lost his mother, when that's the reason why he's involved in this charity in the first place (as it's as much for helping children who have been bereaved as it is about helping people who have been bereaved by the loss of a child). I wouldn't discredit the feeling of having lost a parent at such a young age or say that it's incomparable to having lost a child - unless you've gone through both you can't really say which is worse. My favourite part, though, is the somewhat more subtle implication that Catherine isn't actually pregnant, and that she's faking it.