Endocrinology of Parturition Flashcards
What is the mean duration of human singleton pregnancy?
280 days or 40 weeks from the first day of the last normal menstrual period
What is meant by “Term”?
Period from 37 to 42 weeks
What is meant by “Preterm”?
Delivery before 37 weeks
What is meant by “Post-term”?
Pregnancy beyond 42 weeks
Four phases of pregnancy:
Phase 1: Quiescence
Phase 2: Activation
Phase 3: Stimulation
Phase 4: Involution
Where is the majority of relaxin produced during pregnancy?
Corpus luteum
Which hormones play a role in phase 1?
P4 Relaxin hCG CRH NO
Which hormones play a role in phase 2?
E3 P4 Ferguson reflex CRH Relaxin PGE
Which hormones play a role in phase 3?
PGE OT Relaxin CRH Inflammatory reaction Surfactant Protein A
Which hormones play a role in phase 4?
OT
inflammatory reaction
How do estrogen and progesterone act in myometrial quiescence?
Through an increase in cGMP
Three major effects of prostaglandins:
- ) Stimulate uterine contraction
- ) PGF2alpha promotes formation of gap junctions between uterine SM cells for contractions
- ) Ripens, dilates, thins the cervix
What does PGE2 and PF2alpha do?
PGE2: dilates cervical blood vessels and leads to cervical ripening
PF2a: increases total GAGs activity
What occurs in phase 2?
Increased OT receptors
Estrodiol increased
Increased levels of CRH in phase 2 leads to what?
Fetal cortisol stimulation of prostaglandin synthesis
What is responsible for fetal lung maturation?
Glucocorticoids
How can CRH induce spontaneous labor?
CRH stimulates fetal ACTH release stimulating GC production; once CRH stops GC production it means the babies lungs are ready and labor inducing forces begin
Two way oxytocin induces uterine contractions:
- ) Stimulates release of PGE2 and PF2a by activation of PLC
- ) Directly causes myometrial contractions through PLC -> Ca2+ intracellularly
What is puerperium?
From delivery of placenta through first few weeks after delivery (6 weeks)
Repair processes post-partum occur in what three phases?
Immediate: 24 hours
Early: 7 days
Remote: 6 weeks
What contributes to postpartum depression?
Precipitous drop in estrogen and progesterone
Effect of P4 on milk production?
Suppress milk production during pregnancy by inhibiting PRL
Most important galactopoietic hormone?
Prolactin
Most important galactokinetic hormone?
Oxytocin
What is the milk ejection reflex?
Stimulation by nipple sucking sends signals to the hypothalamus to release OT from posterior pituitary where it bind smooth muscle in mammary glands and they contract
Four stages of lactation:
Stage I: Mammogenesis-preparation of the breasts
Stage II: Lactogenesis- synthesis and secretion of milk
Stage III: Galactopoiesis- maintenance of lactation
Stage IV: Involution- return to non-lactating breasts
When does mammogenesis occur?
12 weeks before delivery; colostrum is present the first rich milk
When does lactogenesis occur?
2-3 days after birth when the milk comes in; P4 drops PRL stays high
What is the organization of secretory tissue in breast?
Alveolus organized into lobules which drain into ductules which widens at the ampulla and drain into the lactiferous duct
What is contained in colostrum?
Protein and minerals (low in carbs/fats)
Antibodies to for passive immunity
Laxative for first bowel movements
What is galactopoiesis?
Production of milk; a supply and demand system
Effects of lactation on GnRH?
Inhibits GnRH release and therefore release of FSH and LH and the ovarian cycle is inhibited
Medications that improve milk production?
Metoclopramide
Sulpurude
Intranasal oxytocin
How does metoclopramide work?
Increases PRL levels
How does sulpurude work?
Dopamine antagonist
Drugs to suppress lactation?
Bromocriptine
How does Bromocriptine work?
Dopamine agonist
