SGW - 8 (pregnancy) Flashcards
tissue constitute placenta barrier in 1st trimester?
syncytiotrophoblast
cytotrophoblast
connective tissue (around foetal capillaries)
fetal capillary (circles)
placenta barrier in 3rd trimester?
syncytiotrophoblast
foetal capillary endothelium
when does hCG peak?
at 8 weeks of pregnancy
rises from 4th week
then trails off from 8th week
effects of maternal smoking on placenta?
reduced placental blood flow
therefore poorer foetal nutrition will REDUCE BIRTH WEIGHT (by about 200g)
how does alcohol cross the placenta? causing?
by diffusion - lipid soluble (also small molecule)
can cause FAS - low foetal weight and growth retarded
(possibly mental retardation, head + facial abnormalities)
why might cytomegalovirus be a health hazard in pregnancy? (normally common cold)
can cause teratogenesis
process by which congenital malformations are produced in an embryo or fetus
what is given to prevent haemolytic disease of the new born?
anti-D therapy (antibodies) - prophylaxis given to mother
to neutralise the antigens in the mother’s blood
otherwise causes rapid haemolysis when bind to foetal RBC
what is shed in the 3rd stage of labour?
the placenta
maternal tissue: decidua
(foetal: amniochorion membrane)
where does IgG in foetal blood derive from?
mothers blood
why can’t a neonatal immune disease by mediated by IgM?
only IgG can cross the placenta (via pino-endocytosis)
why are the maternal adaptations to pregnancy required?
- provide suitable environment for nutrition, growth and development of foetus
- prepare mother for birth
- prepare mother for support of new born
where is hCG released and when does it peak?
from syncytiotrophoblast of blastocyst
peaking at 10 weeks gestation (pregnancy)
function of hCG?
mimics LH on corpus luteum - preventing degeneration to maintain endometrium lining to support pregnancy via release of progesterone (and oestrogen)
hormones involved in maintaining pregnancy?
oestrogen and progesterone (steroids)
where is hCG released from? function?
cells of developing FERTILISED OVUM
stimulates CL’s released of BOTH progesterone and oestrogen to maintain endometrium, therefore pregnancy
what does hCG mimic?
luteal phase (LH) of menstrual cycle (post ovulation) menstrual cycle = ovarian (oestrogen + progesterone) + uterine cycles (endometrium lining, stratum functionalis + basalis)
what does hCG reduce? why?
maternal IgA, IgG, 1gM
humeral immunity is depressed - stop rejection of placenta
BUT mother - more susceptible to viral infections
function of progesterone? effects on mother?
relaxes SM
can lead to GI: reduced motility –> heartburn + constipation
which oestrogen hormone in maternal serum/urine would best indicate foetal progress? why?
oestriol (E3)
this hormone is dependent on foetal ADRENAL and LIVER metabolism as well as placental function
low oestriol = foetal distress, early delivery may be desirable
which hormones from the anterior pituitary stimulate breast growth?
oestrogen, progesterone, prolactin
how does inhibin (from CL + placenta) prevents further pregnancies?
suppress FSH secretion - blocking follicular growth
what are the changes in glucose which occur during pregnancy to the mother?
- reduction in maternal glucose + AA CONC.
- diminished maternal RESPONSE to insulin (insulin resistance) in 2nd 1/2 pregnancy (save glucose for foetus)
- increase maternal free FATTY ACID, ketone, triglyceride levels (ALTERNATIVE metabolic fuel)
- increased insulin RELEASE to a normal meal
how are the changes to the maternal concentration of glucose achieved in pregnancy?
through combined actions of:
hPL (hCS)
oestrogen, progesterone, prolactin (all anterior pit.)
function of progesterone on maternal appetite during pregnancy?
stimulates appetite in 1st half of pregnancy
diverts glucose into FAT SYNTHESIS
function of oestrogen in pregnancy on maternal appetite?
stimulates an increase in prolactin release (anterior pituitary) - +ve feedback
which hormones generate maternal resistance to insulin?
prolactin (stimulated by oestrogen) hPL (increase maternal appetite) glucose cortisol (stress hormone, release more fatty A - alternative fuel) (possibly oestrogen and progesterone)
what are the effects on maternal glucose usage from all the hormonal changes?
maternal glucose usage declines
gluconeogenesis increases
maximising availability of glucose to foetus
in later pregnancy, how are maternal energy needs met?
by metabolising PERIPHERAL fatty acids
function of progesterone in early pregnancy?
stimulates appetite
increase maternal deposition of fat (divert glucose to fat synthesis)
(about 3kg of fat accumulated by mother)
how is the 25% of maternal weight gain (about 3kg) from progesterone in early pregnancy beneficial to the mother in later pregnancy and after birth of baby?
maternal preparation e.g. breast growth (for lactation - why prolactin involved) and also may provide a reserve (fatty acids) for later pregnancy when foetal demands are greater (for glucose)
what is the transport of glucose across the placenta limited by?
FLOW - simple diffusion
therefore maternal supply
describe the effects of hPL (hCS) on mother during pregnancy
reduced uptake of glucose into maternal cells (from increase PERIPHERAL insulin resistance) - favour foetal supply
hPL LOW in early pregnancy, but increases as placenta grows (released from placenta)
has diabetogenic effect
describe what happens after a maternal meal due to the effects of hPL (hCS) released from placenta? what can it lead to?
maternal meal –> transient maternal HYPER glycaemia –> INCREASE maternal insulin release from pancreas –> (hPL + other hormones) –> DECREASE uptake into maternal cells –> INCREASE availability of glucose to foetus
(can lead to maternal HYPO glycaemia BETWEEN meals)
aside from insulin resistance, what else does hPL (hCS) promote?
lipolysis
how does hPL promote lipolysis?
lipids and ketones released are avaliable for energy
in early pregnancy, PROGESTERONE increases maternal APPETITE and promotes STORAGE of glucose in fat stores
(lipolysis of mother = more glucose for foetus)
