Physiology Of Labour

Question 0

Mechanism of labour

Answer 0

Flex ion
Descent in transverse position  
Internal rotation-> shoulders enter inlet
Delivery by extension
Extant rotation-> shoulders enter outlet 
Ant shoulder
Post shoulder
Body delivers like a fish 
Born head facing down

Question 1

Pelvis measurements

Answer 1

Ant to post 11.2 female 10 male
Diagonal AP + 1.5
Transverse f 13.1 m 12.5
Oblique f 12.5 m 12

Question 2

Labour initiation

Answer 2

Uterine wall becomes more excitable as it is stretched by fetal growth, spontaneous contractions start to occur, small area of myometrium acts as pace maker cell
Placenta becomes unable to meet fetal needs
Maturation of fetal anterior pituitary-> increased fetal ACTH-> increase corticotrophin releasing hormone and arginine, vasopressin
-> cortisol release->placental steroidogenesis-> progesterone to oestrogen->prostaglandins
Uterus released from progesterone block
Increase estrogens->increased sensitivity to contractile agents-> histamine, oxytocin, acetyl choline, prostaglandins
Stimulate contractions-> stimulate post pit.-> oxytocin