For the birth of God as a human being, God was interested in the condition of the mother's womb. For even a great, but imperfect, judge of Israel, Samson, God was directive about the state of the mother during the pregnancy. The request for the mother to be pure is repeated for emphasis.
Judges 13:3f
An angel of the LORD appeared to the woman and said to her, "Though you are barren and have had no children, yet you will conceive and bear a son. Now, then, be careful to take no wine or strong drink and to eat nothing unclean."
Judges 13:7
"But he (the angel) said to me, 'You will be with child and will bear a son. So take neither wine nor strong drink, and eat nothing unclean. For the boy shall be consecrated to God from the womb, until the day of his death.' "