Childbirth and lactation Flashcards
week 8
How is date of delivery estimated?
Estimation = LNMP + 280days (9 months and 7 days) OR via ultrasound (earlier is more accurate)
Why is it important to determine the estimate day of delivery?
booking caesarian,
deciding if to induce labour (high BP or past DD)
, determine if the baby is growing well,
interpreting antenatal screening.
- What are the dates for a) pre-term, b) term and c) post-term
Pre= less then 37 weeks
term = 37-42 weeks
post = more than 42 weeks
What can cause pre-term birth?
uterine over-distension (twins),
infections, antepartum
hemorrhage, previous preterm delivery,
smoking,
maternal diabetes or HTN affecting placenta.
What do prostaglandins stimulate?
more vigorous contractions)
What is the role of Estrogen in the induction of labour?
up-regulates myometrial OT and PG receptors,
induces gap junctions
and opposes uterine relaxant actions of Progesterone.
What is the role of oxytocin (placental and maternal) in labour induction?
increases Ca influx into myometrial cells = lowers excitation
What is the role of Prostaglandins in the induction of pregnancy?
stimulate myometrial gap junctions and soften the cervix via relaxin.
Also stimulates contractions via positive feedback.
How is Progesterone decreased before labour and what does it all0ow for?
withdrawal due to down-regulation of PRs and up-regulation of ERs in uterine muscle.
Allows for myometrial contractability.
What are the three main events of labour initiation?
Placental CRH –> fetal HPA and Adrenal Glands increase cortisol
CRH –> estrogen and prostaglandins
Prostaglandins stimulate contractions.
What are the results (3) of the three events that initiate labour?
cervix softens and increases in elasticity
Myometrium gains capacity to contract forcibly and rhythmically
Maintenance of contractions
What are the stimuli of prostaglandins?
placental CRH/ cortisol
placental estrogen
placental/maternal oxytocin
contractions (positive feedback)
What changes occur to the cervix in pregnancy?
Softened (by relaxin and prostaglandins)
Dilation
Effacement (thinning of cervix from stretching)
When does dilation start, what is it caused by?
Starts
several days before parturition
driven by
E, PG, cytokines and cervical fibrocytes)
caused by
myometrial contractions
What does ‘breech position’ refer to and what are its three positions?
Baby bottom first
complete
footling (one leg first)
frank (bottom first, feet up near head)
What changes occur to the myometrium during pregnancy?
Contractibility (gap junctions and ion channels stimulated)
Hypertrophy
What can be used to delay labour?
Antiprostaglandins, B-agonist (relax smooth muscles) and Ca channel inhibitors.
methods for inducing labour
Use oxytocin, prostaglandins and break amniotic membrane
What are (2) signs of labour onset and what are (2) misleading signs?
Labour
Regular contractions and progressive cervical effacement and dilation
misleading
release of blood-stained mucous from cervix
rupture of membranes
When/defining feature of the 4 stages of labour
Pre-labour
Cervix softenes and becomes stretchable
Stage 1
From the start of regular contractions –> full dilation
Stage 2
Full dilation –> delivery
Stage 3
Baby delivery –> delivery of placenta
What does a APGAR score tell us?
Assess how well the baby is adapting but is NOT an indicator of baby ouctomes.
What makes up the criteria for APGAR test?
A- appearance
P- pulse
G- grimace
A- Activity
R- respirations
What does a APGAR score of 7-10, 4-6 and 0-3 mean respectively?
7-10
-doing well, no resus needed
4-6
-may require assistance with breathing
0-3
-likely resus
What is the role of glucocorticoids in preparing fetus for extrauterine life?
allows for maturation of systems:
-respirartion
-glucose regulation
- thermoregulation
Na/K ATPase activity
digestion enzymes
What structures are present for fetal blood circulation but not neonatal circulation?
Ductus Venosus
Forarmen ovale
Ductus arterisus
umbilical vein and artery
Name some major anatomical features of the breast.
15-25 lobes, subdivided into mammary gland lobules
lobules contain milk-producing alveoli
lobules are separated by fat and CT
CT forms suspensory ligaments
Structure of breast lobules
lobules contain milk producing aveoli –> lactiferous ducts –> lactiferous sinus –> nipple
Compare the histology of nonpreg, preg and lactating breast tissue.
Non
Mostly fat and CT\
Little grandular tissue
preg
Extensive gladnular system with ducts
(alvelor secretion begins 2nd tri)
lactating
Aveoli surrounded by myoepithelial cells
Avelolar lumens filled with milk secretioms
What hormones are invloved in breast enlargement?
PRL, Oxytocin, E, HCS, P and hCG
Describe the milk-letdown reflex
- suckling of nipple
- nervous stimulation of the hypothalamus
- posterior pituitary releases OT
- OT stimulates the contraction of myoepithelial cells → milk ejection
Why doe E and P inhibit PRL?
do not need milk synthesis during pregnancy
compare colostrum and human milk in lactation
Colostrum = yellowish fluid during the first few days after birth, less lactose than milk and almost no fat. It has more protein and vitamin A. Both have IgA antibodies to create immunity.
Describe the positive feedback loop involving oxytocin that occurs in a normal labour.
stretch of uterus by baby’s head –> hypothalamus release GnRH –> pituitary release Oxytocin –> stimulates contractions –> further stretching –> repeats
what hormone is vital for causing maturational change in the foetus at birth?
What does it do?
cortisol (glucocorticoids)
surfactant production in lungs = stops lungs sticking together
glucose regulation (decreases gly deposition in liver)
NaKATPase activity in kidney
