physiology of pregnancy Flashcards
HCG released by trophoblast signals the corpus luteum to continue secreting which hormone?
- progesterone
supply of oxygen to fetus is facilitated by the increased ability of fetal haemoglobin to carry oxygen. The concentration of fetal haemoglobin in a healthy fetus is what % more than the haemoglobin conc of adult blood?
- 50% more
cardiac output in pregnancy increases by?
- 40%
regarding maternal respiratory function in pregnancy does vital capacity increase true or false?
true
regarding maternal resp function in pregnancy is oxygen consumption increased? true or false?
- true
regarding maternal resp function in pregnancy is progesterone predominantly responsible for resp adaptations in pregnancy true or false?
true
regarding maternal resp function in pregnancy is PCO2 reduced? true or false?
true
is von willebrand factor increased in pregnancy true or false?
- true it is increased
what is the typical maternal weight gain in pregnancy?
- 11kg
the third stage of labour is defined as?
- delivery of placenta
prolactin stimulates milk production and is released from which part of the brain?
- anterior pituitary
oxytocin is required for release of milk from breast to suckling infant. it is released from which part of the brain?
- posterior pituitary
the fertilised ovum progressively divides and differentiates into what?
- blastocyst
- moves down from site of fertilisation in upper oviduct to site of implantation in the uterus
at what days does the transport of the blastocyst into the uterus occur?
- 3-5 days
at what days does the blastocyst attach to the lining of the uterus?
- 5-8 days
which part of the blastocyst burrow into the uterine wall and become placenta
- outer cells
- inner cells develop into the embryo
what does the placenta do?
- produces several hormones to maintain pregnancy
cords of what cells - begin to penetrate the endometrium once the free-floating blastocyst adheres to the endometrial lining?
- trophoblastic cells
placenta is derived from what two tissues?
- trophoblast and decidual tissue
trophoblast cells differentiate into what kind of cells?
- multinucleate cells (syncytiotrophoblasts)
what do multinucleate cells do?
- invade decidua and break down capillaries to form cavities filled w maternal blood
developing embyro sends capillaries into the syncytiotrophoblast projections to form what?
- placental villi
villi contains what?
- fetal capillaries separated from maternal blood by a thin layer of tissue - no direct between fetal and maternal blood
how does 2 way exchange occur between mother and foetus?
- largely down diffusion gradient
- resp gases, nutrients and metabolites are exchanged here
at what week in pregnancy is placenta and heart functional?
- 5th week of pregnancy
early nutrition of embryo involves invasion of what cells into the decidua?
- trophoblastic cells
HCG signals the corpus luteum to continue secreting what?
- progesterone
what does progesterone stimulate decidual cells to do?
- to concentrate glycogen, proteins and lipids
as placenta develops it extends what kind of projections (villi) into the uterine wall
- hair-like
how does villi work?
- increases contact area between uterus and placenta allowing more nutrients and waste materials to be exchanged
blood vessels from embryo develop in what?
- in the villi
is the mothers blood and embryo’s blood in direct contact true or false?
- false
- a thin membrane separates the embryos blood in villi from mothers blood in intervillous space
- circulation within the intervillous space acts partly as a AV shunt
the placenta plays the role of the foetals …..?
- lungs
respiratory function of the placenta makes supply of oxygen and removal of what?
- carbon dioxide
is maternal blood considered oxygen rich blood?
- yes
and the umbilical blood (mixing of arterial and venous blood - is considered oxygen poor) - oxygen diffuses from maternal into foetal circulation system
is carbon dioxide elevated in foetal blood true or false?
- true
how does foetal oxygenated blood return to the fetus?
- via umbilical vein
how does maternal, oxygen-poor blood flow back into circulatory system?
- via uterine veins
what 3 factors facilitate the supply of the fetus w oxygen?
- foetal Hb - increased ability to carry O2
- higher Hb conc in foetal blood
- bohr effect - foetal Hb can carry more O2 in low pCO2 than in high pCO2
how does placetal exchange processes occur?
- via classic membranous transport mechanisms
how does water diffuse into placenta?
- along its osmotic gradient
electrolytes follow what substance?
- water
- iron and Ca2+ can only go FROM mother TO child
glucose passes the placenta via what kind of transport?
- simplified transport
- high glucose is required in 3rd trimester
- fetus’ main source of energy
fatty acids diffuse across the placenta how?
- free diffusion
waste products diffusion is based on what?
- concentration gradient
what does HCG do?
- prevents involution of corpus luteum - corpus luteum stimulates progesterone and oestrogen
HCG serum levels increase by how much every 48 hours in a singleton pregnancy?
- levels double
in an ectopic pregnancy what does HCG do?
- remains static or it is slow rising
in a failing pregnancy the HCG can be seen to?
- start falling
ongoing viable pregnancy you will see?
- doubling, or >60% rise
what are some side effects of HCG on mother?
- nausea and vomiting
when is HCG found to be very high?
- in multiple pregnancies or molar pregnancies
what point do levels of HCG begin to fall?
- 12-14 weeks
human placental lactogen is produced at what point of pregnancy?
- week 5 of pregnancy
what does human placental lactogen do?
- involved in protein tissue formation
- decreases insulin sensitivity in mother - allow more glucose for foetus
- also involved in breast development
what does progesterone do?
- development of decidual cells
- decreases uterus contractility
- preparation for lactation
what does oestrogen do?
- allows for enlargement of uterus
- breast development
- relaxation of ligaments
CRH -> ACTH -> aldosterone and cortisol -> ?
aldosterone -> can cause maternal hypertension
cortisol -> can cause inc oedema, insulin resistance -> leading to gestational diabetes
drugs can also cross placental barrier, what drugs are considered as teratogens?
- thalidomide, carbamazepine, coumarins, tetracycline
- alcohol, nicotine, heroine, cocaine, caffeine
- drugs - excluding alcohol -> 3% of all congenital malformations
HCG and HC thyrotropin ->
- can cause hyperthyroidism
increasing Ca2+ demands can cause
- hyperparathyroidism
why is there an increase in CO during pregnancy?
- due to demands of uteroplacental circulation
during labour cardiac output can increase how much?
- 30%
increase in CO can result in what kind of changes in heart?
- ECG changes
- functional murmurs
- heart sounds
-> considered all normal changes
HR increases up to what to increase CO?
- up to 90min to increase CO
blood pressure drops during what semester of pregnancy?
- 2nd trimester
- this is because uteroplacental circulation expands and peripheral resistance decreases
in multiple pregnancies, CO increases more and BP drops more? true or false?
- true
how much lower is BP than pre-pregnancy BP?
- 15mmHg
BP rises in what trimester reaching pre-pregnancy levels again?
- 3rd trimester
does plasma volume increase proportionally w cardiac output true or false?
- true
why when erythropoesis increases, Hb decreases?
- it is decreased by dilution (decreases blood viscosity)
do iron requirements increase in pregnancy?
- yes
- as womens blood vol increases 50%, RBCs only increase by around 30%, this leads to a natural haemodilution
- therefore there is an inc in iron requirements and inadequate iron levels affect huge no of women
- therefore iron supplementation is required.
why does lung function change during pregnancy?
- in response to progesterone
- also because the enlarging uterus interferes w lung function
what does progesterone signal the brain to do regarding respiration?
- signals to brain to lower CO2 levels - inc CO2 sensitivity in resp centres
O2 consumption increases to meet metabolic need of fetus, placenta and mother true or false?
- true
how does body lower CO2 levels in a pregnant women?
- increasing resp rate
- increasing tidal and minute volume
- pCO2 decreasing slightly
- vital capacity and PO2 don’t change
GFR and renal plasma flow increases in pregnancy true or false?
- true
- up to 30-50% peaking at mid trimester - 16-24 weeks
there is an increased re-absorption of ions and water - what is this process driven by?
- placental steroids
- aldosterone
first trimester anaemia in pregnancy as defined as Hb below what level?
< 110g/L
2nd and 3rd trimester anaemia in pregnancy is defined as?
- Hb <105g/L
outwith pregnancy anaemia is defined as Hb between?
- 120-160g/L
is there an increase in urine formation?
- slight increase in urine formation
how does upright position affect renal function?
- decreases renal function
how does supine position affect renal function?
- increases renal function
how does lateral position affect renal function?
- significantly increases renal function
- why in 3rd trimester many women sleep in a lateral position to sleep
due to increased plasma vol and inc GFR following ranges differ in pregnancy - study
ALT decreases <30U/L (5-55)
Urea <3.5mmol/L (2.5-7.8)
creatinine <50umol/L (44-80)
albumin 20-40g/L (30-50)
what changes occur to maternal coagulation?
- in pregnancy womens blood becomes a hypercoagulable state
- reduces risk of haemorrhage during and after delivery however comes w increased risk of VTE
how many extra kcal/day should be ingested by the mother?
- 200 extra kcal/day
> 30g/day extra protein intake
1st-20th week there is a normal or increased sensitivity to insulin? true or false?
- true
1st-20th week there is a normal or increased sensitivity to insulin? true or false?
- true
21st-40th week there is maternal insulin resistance true or false?
- true
due to human placental lactogen, cortisol, and growth hormone
nutritional requirements in pregnancy?
- folic acid (folate) -> reduces risk of neural tube defects
- vit D supplements
- high protein diet, high energy uptake
- iron supplements may be required
- B vitamins - erythropoesis
what is parturition?
- birth of the baby
- towards end of pregnancy, uterus becomes progressively more excitable
progesterone increases contractility towards end of pregnancy true or false?
- false, oestrogen increases contractility, whilst progesterone inhibits contractility
prostaglandins are produced by what structures?
- placenta
- myometrium
- decidua
- membranes
oxytocin - released from posterior pituitary gland - does what to uterus?
- increases contractions and excitability
mechanical stretch of uterine muscle does what?
- increases contractility
does D-dimer decrease during pregnancy?
- no it increases thus why for potential PE in pregnant women, D-dimer is not routinely measured
which factor remains unchanged during pregnancy?
- factor II
is fibrinogen increased or decreased in pregnancy?
- increased
is plasminogen increased or decreased during pregnancy?
- increased
is vWF increased or decreased during pregnancy true or false?
- increased
is antithrombin increased, decreased, or unchanged during pregnancy?
- unchanged
braxton hicks contractions increase toward the end of pregnancy, what are these?
- sometimes known as ‘false’ or ‘practice’ contractions
- caused by muscles of uterus tightening
- felt in front of the body
what else occurs at onset of labour?
- cervical ripening
- stretch of cervix by fetal head increases contractility
- cervical stretching also causes further oxytocin release
- strong uterine contraction and pain from birth canal can cause neurogenic reflexes from spinal cord -> inducing intense abdominal muscle contractions
study physiological changes at onset of labour
what is 1st stage of labour?
- cervical dilation 8-24 hours
what is 2nd stage of labour?
- passage of fetus through birth canal (few mins to 120 mins)
what is 3rd stage of labour?
- expulsion of placenta
what controls growth of ductile system?
- oestrogen
what controls development of lobule-alveolar system?
- progesterone
both oestrogen and progesterone inhibit milk production true or false?
- true
-> at birth there is a sudden drop in these hormones
what stimulates milk production?
- prolactin
-> stead rise in levels of prolactin from week 5 till birth
-> 1-7 days after birth, prolactin induces high milk production
-> stimulates colostrum (low vol, no fat)
oxytocin is responsible for what process?
- ‘milk let-down’ reflex
what stimulates the milk let-down reflex
- stimulated by baby’s suction on nipple
what happens after baby has attached to nipple in milk let-down reflex?
- impulses are propogated in spinal cord
- to higher brain centres
- causing stimulation of hypothalamic nuclei
- release of oxytocin from posterior pituitary
- milk is then ejected at the nipple