@Piggywaspushed
Yeah, there's stuff on there like congenital birth defects : I haven't heard of anyone attributing having an extra finger to the AZ vaccine yet but there's always time...
My dd was born without an arm, and one of the first things I asked was it something I'd eaten/done.
I was told that when you get limb defects due to medication then it effects both sides in some ways*-not always the same amount, but it would be almost unheard of for it to cause a missing arm on one side, and no limb difference on the other.
Didn't stop a lady chasing me through Guildford once lecturing me of the dangers of thalidomide. 
*Just to note there are other reasons why a child might be born missing more than one limb, genetic being one.
But a single limb deficiency, with no other issues, which is 99% of cases in congenital cases, they don't really know why it happens, but they are certain it isn't anything you've done/taken.