Luke 1:58

‘And her neighbours and her kinsfolk heard that the Lord had magnified his mercy towards her, and they rejoiced with her.’

We need not assume that they had just heard. This is a catch all phrase. They had all heard in one way or another that the one whom they had all thought barren had become pregnant and now they came to rejoice with her at his birth. Such events were never private. All wanted to join in the celebrations.