I was with my four year old great niece yesterday and she was talking about Jesus and I told her that God made her just the way He wanted her to be while she was in her mommy's belly and she asked me, 'How did He do that?" and it's like how do you explain DNA to a four year old..the same way it was explained to David...she was formed in the mother's womb and God saw what she was going to be before she was born! God shaped her (and us) and we were knitted together..
Psalms 139th Chapter says...
For you created my inmost being;
you knit me together in my mother’s womb.
14I praise you because I am fearfully and wonderfully made;
your works are wonderful,
I know that full well.
15My frame was not hidden from you
when I was made in the secret place.
When I was woven together in the depths of the earth,
16your eyes saw my unformed body.
All the days ordained for me
were written in your book
before one of them came to be.