CAUSES OF ONSET OF LABOR
- In a woman when pregnancy reach at term and why a pregnant woman feels labor pain and how contraction started and delivery occur
- When fetus matures at term of pregnancy fetal hypothalamus get activated and Release CRH( corticotropin releasing hormone)
- This corticotropin releasing hormone stimulates fetal pitutary gland .
- Due to stimulation of CRH fetal pitutary gland secreate ACTH( Adrenocorticotropic hormone)
- This ACTH stimulate fetal adrenal glands.
- Due to stimulation of ACTH fetal adrenal gland secreate cortisol and dwhydroepiandrosterone sulphate.( DHEAS)
- DHEAs go to the placenta and converted to oestrogen.
- Cortisol go to placenta and placenta secreate estrogen and Prostaglandin.
- Prostaglandin secret from decidua, fetal membrane, amnion and chorion and from placenta.
- Here estrogen secreation increase and progesterone secreation decrease.
- Due to this estrogen and progesterone ratio alter .
- This rise in estrogen level stimulates maternal pitutary gland to release oxytocin.
- High level of estrogen increase oxytocin receptor in myometrium
- High level of estrogen cause secretion of Prostaglandin.
- Due to oxytocin and Prostaglandin labor pain starts due to uterine contraction.
These are all steps why labour pain starts in pregnancy.
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