Birth Flashcards
1
Q
What preparations must be made in the foetus before delivery?
A
- Lungs must develop surfactant
- AV shunts, foramen ovale, ductus arteriosus must close
- GIT must mature
- Kidneys must be able to regulate ECF + acid-base balance
- They must be able to generate own heat for thermoregulation
- There must be a change from foetal to adult Hb
2
Q
What is the role of glucocorticoids before birth?
A
- They are vital for foetal organ development and timing of birth
- Their levels rise towards the end of pregnancy
- Secreted by foetal adrenal cortex
- Prepartum cortisol surge: negative feedback overridden before birth
- If there is a risk of pre-term birth, it is administered as it stimulates early foetal development
3
Q
What are uterotropins? What are their role in labour?
A
- These prepare myometrium for labour
-
Oestrogens:
- Increase
- Stimulate contractile proteins
- Oxytocin/prostaglandin receptors + gap junctions in myometrial cells
-
Progesterone:
- Decreases
4
Q
What are uterotonins? What is their role during labour?
A
- These stimulate contractions of the myometrium during birth
-
Oxytocin:
- From post. pituitary and placenta
- Correlates with Braxton-Hicks contractions, involved in ferguson reflex
-
Prostaglandins:
- PGE2 and PGF2-alpha
- Synthesised in placenta dye to increase in oestrogen
- PGE2 administered to induce labour
- PGF2-alpha is a physiological uretonin
5
Q
What are the 4 hormonal phases of labour?
A
- Phase 0: inhibitory effects of porgesterone, prostacyclin and NO
-
Phase 1: towards end of pregnancy, oestrogen stimulates:
- Production of contractile proteins in myometrial cells
- Production of receptors for prostaglandins and oxytocin
- Production of gap junctions on myometrial cells
- Phase 2: myometrium contracts under influence of oxytocin and prostaglandins
- Phase 3: after birth, sustained contractions reduce the size of postpartum uterus
6
Q
What are the three stages of labour?
A
-
Stage 1:
- Regular painful contractions followed by periods of relaxation
- Uterine volume decreases
- Dilations and shortening of cervix until cervix is fully dilated
-
Stage 2:
- Full dilation of cervix = cervix pulled upwards
- Delivery of neonate = pushed down by contractions
-
Stage 3:
- Placenta detaches and is expelled
7
Q
What changes occur during labour?
A
-
Cervical ripening:
- Weeks/days before birth
- Loss of collagen, increased compliance
- Prostaglandins F2-alpha and E2, relaxin and NO
-
Myometrial changes:
- Regular, short contractions during labour
- Increased oestrogen = increased myometrium bulk and oxytocin receptors
- Decreased progesterone = myometrial activity enable and production of oxytocin receptors
- Oxytocin, PGF2-alpha and PGE2 increase myometrial activity
8
Q
What are the stages of lactation?
A
-
Stage 1:
- Mid-pregnancy to 2Ds postpartum
- Glands differentiate
- Capable of secreting small quantities of some milk components
- Colostrum produced 2D after childbirth
- Progesterone inhibits lactation - decrease triggers onset
-
Stage 2:
- Secretion of copious milk
- Decreased progesterone + increased prolactin = secretion
- Change in permeability between epithelial cells
- Change in secretion of protective substances
9
Q
What is the effect of suckling?
A
- Suckling increases prolactin and oxytocin
- Prolactin is for galactopoiesis
- Oxytocin is for the let down reflex
10
Q
What is galactopoiesis?
A
- Maintenance of milk production
- Requires prolactin to act on alveolar epithelial cells
- Requires milk to be removed regularly
11
Q
What is the let down reflex?
A
- Milk ejection
- Oxytocin stimulates contraction from myoepithelial cells
- Allows pressurised milk to exit
-
Reflex:
- Stimulation of mechanoreceptors in nipple
- Thoracic nerves + spinal cord
- SON + PVN of hypothalamus release oxytocin
