"How is it gossip? Gossiping is malicious and spreading rumours and unconfirmed facts."
Ahem:
www.google.co.uk/amp/s/dictionary.cambridge.org/amp/english/gossip
Note the "unkind" - gossipy people aren't necessarily deliberately malicious, but thoughtlessly & selfishly speak out of turn because they're more concerned with making themselves appear a certain way (more informed than the person they're gossiping to, "closer" to the person they're gossiping about etc).
Your response to her reaction op is VERY telling.
Most people, even if they disagreed with your friend, would have let it go, certainly by this point and certainly wouldn't try to argue the point as vehemently as you are, albeit on an anon forum.
Your friend is dealing with a difficult end to her pregnancy, one which nobody would feel is ideal and could well indicate a potentially distressing outcome, plus the usual feelings of vulnerability and hormonal fluctuations, sleep deprivation etc - yet you are FAR more concerned with whether you are "in the right" and if SHE has acted as a decent friend to YOU!
Seriously? That's what you think is important right now? As they say, with friends like you...
"FWIW the sister of one of the girls in our WhatsApp group messaged said friend and wished her luck for her section and they’re being pilloried for passing on their best wishes." Why does this surprise you? Why would the SISTER of a friend necessarily A be told in the first place B feel it at all appropriate to comment directly?
This poor woman who has just had a baby via a MAJOR operation, which was likely necessary due to MEDICALLY concerns that a vaginal delivery was too risky for either mother, baby or both and is being subjected to gossipy crap and expected to worry about the hurt feelings of people who AREN'T the ones who've just been through that and aren't even family! Honest to god you should all just bloody leave her alone!
In extreme bad taste for you to think causing her further distress at this time is amusing!
You may have had 3 yourself, that DOESN'T mean you know how she feels or what worries she's had to deal with.
"You can never be wrong, can you OP. There's always so-and-so's friend's sister's experience available to back you up, isn't there." Yep definitely "that type" aren't they?
"Please explain how OP can possibly be viewed as a 'friend' to this woman." I'd be interested to know that too. Friends are supportive and kind when you're going through a difficult stressful time, not critical of how you feel and how you respond to that stress.