Yeah woman can be catty but by the same token women know when they’re getting the backhanded compliment. The fat girl is well aware what her so-called friends are doing. She just doesn’t have the self-esteem to tell them to go fuck themselves.
In person you might get the self-deprecating ‘oh you’re so lucky not to have kids’ when catching up with a childfree friend, but it doesn’t tend to work like that online. Mothers who regret it commiserate online with other mothers, not the childless. Childfree threads draw the attention of mothers who say they have no regrets and they post to tell the childless they should have kids too because they’ll never understand what real love is if they don’t, despite the long-term horrors pregnancy and childbirth can inflict on a woman.
Anyway, the only thing approaching a survey on this topic I could find with a cursory search was
this which said the majority (75%) of childfree women don’t regret not having kids. It’s still a relatively new area I guess.