18 Now the birth of Jesus Christ was on this wise: When as his mother Mary was espoused to Joseph, before they came together, she was found with child of the Holy Ghost. 19 Then Joseph her husband, being a just man, and not willing to make her a publick example, was minded to put her away privily. 20 But while he thought on these things, behold, the angel of the Lord appeared unto him in a dream, saying, Joseph, thou son of David, fear not to take unto thee Mary thy wife: for that which is
conceived in her is of the Holy Ghost
Matt 1:18-20 (KJV)
26 And in the sixth month the angel Gabriel was sent from God unto a city of Galilee, named Nazareth, 27 To a virgin espoused to a man whose name was Joseph, of the house of David; and the virgin's name was Mary. 28 And the angel came in unto her, and said, Hail, thou that art highly favoured, the Lord is with thee: blessed art thou among women. 29 And when she saw him, she was troubled at his saying, and cast in her mind what manner of salutation this should be. 30 And the angel said unto her, Fear not, Mary: for thou hast found favour with God. 31 And, behold,
thou shalt conceive in thy womb, and bring forth a son, and shalt call his name JESUS.
Luke 1:26-31 (KJV)
Conception requires an egg. The angel did not say to her she would incubate.