Question

Under the effect of that hormone which organ of the femal reproductive system start to contract and thereby birth process is facilitated

Answer 1

ovary release egg (ova) and penis release sperm during mating after copulation sperm get working in uterus and after 2 month get fertilize from ova and make gamet after1month gamet forming zygote then that place a process started which is called embryogenesis .It is also work for birth because Making of embryo in fetous this process called embryogenesis .After making fetous a baby complete in uterus after 9 month baby is able to come out from mother body.
The hormones are oxytocin, estrogen, oestrogen.