…I’ve seen a few posts along the lines of, “Why are there children on Gallifrey? Time Lords can’t have children, that’s why they use Looms to procreate.”
Ok, so, we know that there is no canon in Doctor Who, so Looms are not canon.
Looms have only been mentioned in the novels, they have never been mentioned in the TV series…and, to the best of my knowledge, they haven’t been mentioned in the audios (feel free to correct me if I’m wrong on that). Not only that, but there are many references in the TV show that directly contradict the existence of Looms. “There have been many statements by the Doctor in televised and non-television based media referring to him being a “boy” or showing other Time Lords as children. In The Time Monster the Doctor tells Jo a story referring to when he was a “little boy”. In The Sound of Drums and The End of Time, the Master is shown in flashback sequences as a child.“ [src]
Also, importantly, “The Eighth Doctor once said that he was loomed, yet remembered having parents and a childhood. He knew that one of these was a dream, but could not recall which.” [src] Again, this was in one of the novels, so the novels themselves have cast doubt on the existence of Looms.
It seems very clear that Looms are not part of the current Doctor Who lexicon.* One could posit a possible timey wimey explanation, if you want to keep Looms within your personal Doctor Who canon, that at some point through Time Lord (or otherwise) interference in the time stream, the Time Lords were rendered sterile (through Pythia’s Curse) necessitating the use of Looms for the purpose of procreation. Then, at some point someone went back and undid that, and so Looms were now never necessary for Time Lord procreation.
However, if you really want to talk in traditional fandom terms about canonicity. Even though there is no canon in Doctor Who. Purely for the sake of argument and lacking a better term (although I really like lexicon*), while the audios have been brought into the “canon” by being reference in The Night of The Doctor, the novels have steadfastly remained outside the canon since the start of NewWho, not least because some of them have been directly adapted as tv episodes featuring a different Doctor (ie. Human Nature). Now, you can use timey wimey reasoning to explain why The Doctor could have lived through the same events twice in different incarnations (and, personally, I rather enjoy that), but it does suggest that if there was a Doctor Who canon, which there isn’t, the audios would be in it but the novels wouldn’t.
TL;DR – Looms are not part of current Doctor Who continuity and that’s why there were children on Gallifrey.
*lexicon – a list of terms relating to a particular subject [src] World English Dictionary