Mary knew of the pregnancy of Elizabeth, her own relative, only at the 6th month when the Angel revealed this to her. It was great news for Mary to be told that God had turned an impossibility for her relative into a possibility. For her to believe that this same possibility that the Angel had prophesied in her own life would take place, it required that she confirmed first the case of that of Elizabeth, her relative.

That's why she arose with haste to the city of Judah and straight to the home of Elizabeth. "How could Elizabeth keep such wonderful news for such a long time without communicating it to her", she must have thought. 

For Mary to know that what the Angel had said, had already taken place in her own life, the Spirit and Power of God in Mary moved in the life of John in the womb of Elizabeth so that Elizabeth would testify that she was pregnant.

The words of Elizabeth's testimony proved to Mary that  she too had become pregnant as Elizabeth, just as the Angel had told her. This was significant.

Mary could no longer blame Elizabeth for keeping the good news to herself just as Elizabeth would have blamed Mary for not sending her word that she too was pregnant.

It was all joy as they met. They believed God and worshipped Him for the fulfillment of the things which had been spoken.

Glory be to God.