How is a human child being born a supernatural event?
Not a child being born a child being conceived supernaturally, via the Holy Spirit, AKA God.
From free Christian teaching.
CONCEPTION AND WEEK 1
The new cell has inherited 23 chromosomes from each parent, making a total of 46 chromosomes. We will study DNA a little later. DNA is God's design code in each one of us.
The fertilised egg travels down the fallopian tube into the womb (the uterus) where the lining (the endometrium) has been prepared for implantation of the egg.
Nourishment for the little baby is provided by the mother through the umbilical cord.
The baby's blood system and the mother's blood system are completely separate & distinct. Oxygen, and all the necessary building elements and nutrients are transferred from the mother to the baby via the umbilical cord.
It is a miracle!
WEEKS 1 - 4
The developing baby signals his or her presence through placental chemicals and hormones, preventing the mother from having her monthly period. During these four weeks, first the brain, spinal cord and nervous system are formed. Then the heart begins to beat and muscles, limbs, ears and eyes appear. The baby's body is being carefully made by God according to the design on the baby's genetic code, the DNA. God designed the DNA for each one of us.
The Bible says: "For you did form my inward parts: you did knit me together in my mother's womb. I will praise you, for I am fearfully and wonderfully made", Psalm 139 vv.13,14.
In other words, God made you and me in our mother's womb. We are little people, not foetuses, in our mother's womb, being "wonderfully made", according to our genetic design code, our DNA.
I do not know how our heavenly Father, (Yes He is yours aswell Bhavv.) biologically got the other half of the genetic information, inside the egg. Though if He is the creator of everything, I do not suppose it was too difficult.