4 Stages of Childbirth

Gestation period, which is the number of days a woman used to conceive her baby, usually lasts between 37 and 42 weeks.

Secondly, when the birth process is about to begin, the cervix
will thin, softens and relaxes. This is because, a hormone produced in the brain, oxytoxin is released in greater quantity in the woman when the labor begins, making the cervix to dilate and the uterus to contract.

The brain senses that gestation period is complete thus causing the pituitary gland to begin releasing oxytoxin.
childbirth
Thirdly, during pregnancy, a hormone known as progesterone will prevent the uterus from contracting. However, during the beginning of labor, the placenta stops producing progesterone. Therefore, without the restriction cause by progesterone, the uterus will begin to contract.

Lastly, after between 8 and 13 hours of labor, the baby is pushed out through the relaxed and dilated cervix, while the placenta is also removed.