A baby is going to be created when a mother and a father goes through sexual intercoarse. You see the egg cell will be fertelized by the sperm cells that father gives, after that they will fuse to become one thing, think about it like Goku and Vegeta fusing, when they fused they become a zygote, then they will just keep deviding until implantation when it implants in the mothers uterus.
Thats a long process.
Then a process called the gastrulation process happened and then it reaches the embryo stage where the baby finally goes through ectoderm, endoderm and mesoderm, these 3 stages creates the baby's skin and organs.This process takes about 40 weeks
40 WEEKS !!!!
It's getting late, gotta start moving now. Good bye