Prostaglandin E2, which softens the cervix so it can dilate or open in preparation for childbirth.
(dilate means to open wider, chiefly used for eyes and for childbirth)"The pupils of the eye automatically dilate to admit more light in dim conditions.""It was several hours into labor before the birth canal began to dilate."
The hymen doesn't increase in size after childbirth. During vaginal childbirth the hymen is often torn.
Histamine
Almost all the veins and arteries constrict and dilate during heavy exercise. Even capillaries bring a flush to the face and skin by dilation.
I don't know
sepa
During Childbirth a womans reproductive organs are made to be ripped, stretched, expand and a variety of different tramas. this is why it can take up to six weeks to recover from childbirth.
Modern pain relief for childbirth generally involves the use of medication.
The uterine walls
When a mother dies during childbirth.
No it will not return about 2 months after.