3 Endocrinology and parturition

Question 1

For endocrinology see topic 7.

Answer 1

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Question 2

What are the phases of parturition

Answer 2

1) Quiescence
- myometrial contractions are inhibited, primarily by progesterone as well as other hormones.

2) Activation
- during the last 6-8 weeks
- uterine stretch and increased cortisol being to activate the myometrium for contractions
- the placenta releases CRH, stimulating fetal cortisol produciton, which then stimulates surfactant.
- surfactant appears to be another factor with induces labor.

3) Stimulation
- Placental CRH release is itself potentiated by cortisol, so a feed forward loop is established.
- Upon progesterone levels dropping near the end of pregnancy, the uterine contractions are disinhibited and labor can begin.
- Oxytocin stimulates myometrial contractions

4) Involution
- large increase in oxytocin release, initiating the final phase of labor, placental separation, and continued uterine contracitons.