Kay's abortion Following on similar thread

My take, for what it is worth!

I too believe, it was a miscarriage [caused by the bedroom shooting trauma]

If it was an abortion [unconvincing indeed] Neri undoubtedly could / would have made discreet inquiries “to hunt down the doctor” who dared to abort Michael Corleone's child and the doctor would be sleeping with the fishes

From what we saw in the movie -
1. Kay told Michael, when they were dancing at Anthony's party [they seemed happy and Kay sounded genuine] the baby felt like a boy
2. Kay was a virtual prisoner at the Tahoe estate while Michael was away

If Kay wanted / needed to see her Obstetrician / Gynaecologist, agree, Tom would either have arranged a home visit to Tahoe or Kay would have been escorted to the medical clinic and escorted straight back to Tahoe, after the consultation

No doctor especially the family doctor would dare perform an abortion on Michael Corleone's wife
They would “realize what will happen as a result” of aborting Michael Corleone's child – sleeping with the fishes

I doubt there would have been any divorce/child custody hearing [Kay didn't seem to have any visitation rights even] as Michael would “use all his power to keep something like that from happening”