Luke 1:30 And the messenger said to her, ‘Fear not, Mary, for thou hast found favour with God; 31 and lo, thou shalt conceive in the womb, and shalt bring forth a son, and call his name Jesus; [Young's Literal Translation]
Union with sex cells/gametes usually occurs in the fallopian tube, forming the first new cell, the zygote, then after several cell differentiations a multi-celled morulla implants in the womb. This implanting is the moment a woman is pregnant, she has conceived in her womb. Some rare occasions the fertilization occurs outside of the fallopian tube and the morulla doesn't make it to the womb/uterine lining, and an ectopic pregnancy is begun/conceived.
Fertilization, the union of the two sex cells (one male/one female) is done routinely in a lab now, so this is not conception since no host womb is yet involved. Is there new life in the 'petri dish'? Absolutely, but no woman has yet conceived.
God created the morulla WHO implanted in Mary's womb. There is no word from God that GOD used a sex cell from Mary to accomplish this impregnating morulla. The Bible states the child conceived in Mary, not the child conceived of Mary.
Meant to ping you
(Just speculating, not being careless of God's prerogatives.)
Backing up a little in the scheme of things, time we looked at Genesis 38 as to a deeper meaning, eh?