Problems with Labour Flashcards
What is labour?
The physiological process by which a fetus is expelled from the uterus to the outside world
What does the process of labour involve?
The sequential integrated changes in uterine decidua, and myometrium
What tends to precede uterine contractions in labour?
Changes in the uterine cervix
How do Braxton-Hicks contractions differ from labour?
They do not cause the cervix to dilate
What are the two main goals of uterine contractions in labour?
- Dilate cervix
- Push fetus through birth canal
What are the three P’s of labour problems?
- Powers
- Passenger
- Passage
What effect does the oestrogen/progesterone ratio have on the uterine musculature in labour?
It changes to increase excitability
What effect does progesterone have on the uterine musculature in labour?
It inhibits contraction by reducing the excitability of muscles
What effect does oestrogen have on the uterine musculature in labour?
Increases gap junctional communication between smooth muscle cells, increasing contractility
What effect does oxytocin have on uterine musculature during labour?
Increases excitability
Where is oxytocin secreted from?
Maternal posteiror pituitary gland
What effect does mechanically stretching uterine smooth muscle in labour have?
Increases contractility
What does cervical stretching elicit in labour?
Uterine contractions
How do fetal effects contribute to labour?
- Fetus produces hormones which increase glucocorticoids from the placenta, which inhibits progesterone.
- Fetal oxytocin is produced
What can be given to induce labour?
Prostaglandins
How can prostaglandins be given to induce labour?
Oral or into vagina
Give an example of when labour may need to be induced
In pre-eclampsia
What are prostaglandins?
Powerful contractors of smooth muscle
What are prostaglandins involved in, regarding the cervix?
Cervical softening
What stimulates prostaglandin synthesis in labour?
- Increase in oestrogen:progesterone ratio
- Mechanical damage
What synthesises prostaglandins in pregnancy?
- Placenta
- Decidua
- Myometrium
- Membranes
What happens to prostaglandin synthesis in the third trimester?
There is increased synthesis by the amnion
What happens to the levels of prostaglandins in amniotic fluid very early in labour?
They rise
What is cervical ripening due to?
Oestrogen, relaxin, and prostaglandins breaking down the connective tissue