John Calvin Commentary Luke 1:41

"And it came to pass, when Elisabeth heard the salutation of Mary, the babe leaped in her womb; and Elisabeth was filled with the Holy Spirit;" — Luke 1:41 (ASV)

When Elisabeth heard It is natural that sudden joy, on the part of a pregnant woman, should cause a motion of the child in her womb; but Luke intended to express an extraordinary occurrence.

No good purpose would be served by involving ourselves in intricate questions about whether the child was aware of the presence of Christ or felt an emotion of piety: it is enough for us that the babe started by a secret movement of the Spirit.

Luke does not say that the feeling belonged to the child, but rather intimates that this part of the divine operation took place in the mother herself, that the babe started in her womb.

The expression, she was filled with the Holy Ghost, means that she was suddenly endowed with the gift of prophecy to an unusual extent. For the gifts of the Spirit had not previously been lacking in her, but their power then appeared more abundant and extraordinary.