Physiology of Pregnancy and Lactation Flashcards
what is the timeline for fertilised embryo moving into the uterus
day 1 = fertilisation in ampulla
day 3-5 = transport of blastocyst into the uterus
day 5-8 = blastocyst attaches to lining of uterus
what do the inner cells of the blastocyst develop into
the embryo
what are the outer cells of the blastocysts and what do they do
trophoblastic cells
- penetrate the endometrium and burrow into the uterine wall
- will become the placenta
how long does it take for the trophoblastic cells to burrow deep enough for the blastocyst to become buried in uterine lining
12 days
what is the placenta derived from
trophoblast and decidual [endometrium] tissue
how are placental villi’s formed
Trophoblast cells differentiate into syncytiotrophoblast»_space; invade decidua»_space; break down capillaries»_space; form cavities filled with maternal blood
Developing embryo sends capillaries into these projections»_space; placental villi’s formed
by when is the placenta [and foetal heart] functional by
5th week of pregnancy
where does the early nutrition of the embryo come from
the invasion of trophoblastic cells into the decidua
what is the role of HCG in the nutrition of the embryo
signals the corpus luteum to continue secreting progesterone»_space;> stimulates decidual cells to concentrate glycogen, proteins and lipids
what does the placenta essential work as
physiological arteriovenous shunt
- due to circulation within the intervillous space between mother and foetus blood
what is another key role of the placenta
plays as role as fetal lungs
- Oxygen diffuses from the maternal into the fetal circulation system
- CO2 follows reverse gradient
how does Fetal, oxygen saturated blood return to the fetus
via the umbilical vein
how does maternal, oxygen-blood blood return to the mother’s circulation
via uterine veins
what 3 factors facilitate oxygen transport in fetus blood
fetal Hb - increased ability to carry O2
higher Hb conc in fetal blood
Bohr effect - Fetal Hb can carry more oxygen in low pCO2 than in high pCO2
how does water and electrocytes diffuse across the placenta
water diffuses along osmotic gradient
electrolytes follows water
what are the only electrolytes that can go from mother to child
iron and calcium
how does glucose get across the placenta
simplified transport
what role does HCG have in fetal development
effect on the testes of male fetus - development of sex organs
prevents corpus luteum degrading
from when is HCS produced
around week 5 of pregnancy
what effects does HCS have
growth hormone-like effects: protein tissue formation.
decreases insulin sensitivity in mother: more glucose for the fetus
involved in breast development
what is the function of progesterone
development of decidual cells
decreases uterus contractility
preparation for lactation
what is the function estrogens
enlargement of uterus
breast development
relaxation of ligments
what is an indicator of vitality of the foetus
estriol level
what affect does the placenta releasing CRH have on the mother
increases ACTH
» increases aldosterone
» increases cortisol
what does the increase in aldosterone cause
hypertension
what does the increase in cortisol cause
oedema
insulin resistance»_space; gestational diabetes
what affect does the placenta releasing HCG have on the mother
hyperthyroidism
what affect does the placenta increasing calcium demands have on the mother
hyperparathyroidism
what are cardiovascular maternal changes seen in pregnancy
Increase in CO [due to demands of fetal circulation]
HR increases
BP drops during 2nd trimester
where does CO normally sit in pregnancy
30-50% above normal
- beginning week 6 gestation and peaking around 24 weeks
what are all normal changes seen in pregnancy in the mother - in relation to the heart
ECG changes
functional murmurs
heart sounds
how does CO change in the last 8 weeks of pregnancy
decreases as uterus compresses vena cava
what can the HR increase up to in pregnancy
90/min
what are haematological changes seen in pregnancy
plasma volume increases proportionally w/ CO
erythropoesis (RBC) increases
» Hb decreases by dilution
iron requirements increases»_space; supplements may be needed
what causes resp changes seen in pregnancy
increasing progesterone
enlarging uterus
increasing O2 consumption
how does progesterone affect resp
signals the brain to lower CO2 levels
how does the body work to lower CO2 levels
RR increases
Tidal volume increases
pCO2 decreases slightly
Vital capacity and PO2 don’t change
what urinary changes are seen in pregnancy
GFR and renal plasma flow increase
when does the increase in GFR and renal plasma flow increase
@ 16-24 weeks
how can postural changes affect renal function
upright position decreases
supine position increases
lateral position increases
what is pre-eclampsia
pregnancy induced hypertension + proteinuria
what leads to the proteinuria
Kidney function declines: salt and water retention - oedema formation (esp hands and face)
Renal blood flow and GFR decreases
what is the single most significant risk of getting pre-eclampsia
having had pre-eclampsia previously
what are other RF for pre-eclampsia
pre-existing hypertension, diabetes autoimmune diseases (eg lupus) renal disease FHx of pre-eclampsia obesity women with a multiple gestation (twins or multiple birth)
what are SX of eclampsia
vascular spasms, extreme hypertension, chronic seizures & coma
what is the Tx of eclampsia
vasodilators and c-section
what is the average maternal weight gain
24lbs
what causes insulin resistance in pregnancy
HCS
cortisol
growth hormone
what is the special nutritional needs in pregnancy
high protein iron supplements vitamin B folic acid Vit D3 + Ca2+ supplements
what is given before labour to prevent intracranial bleeding
Vitamin K
what is parturition
birth of baby
how does the Estrogen:Progesterone ratio help in labour
progesterone inhibits contractility while estrogen increases contractility.
where is oxytocin made
maternal posterior pituitary gland
what is the function of oxytocin
increases contractions and excitability
what are Braxton Hicks contractions
sporadic uterine contractions
what does cervical stretching cause
further oxytocin release
what effect does oxytocin have on the placenta
stimulates it to make prostaglandins which stimulate more vigorous contractions of the uterus
what are the 3 stages of labour
1st stage: cervical dilation (8-24 hours).
2nd stage: passage through birth canal (few min to 30 min).
3rd stage: expulsion of placenta.
what inhibits milk production
oestrogen
progesterone
what stimulates milk production
prolactin
what does oxytocin do
causes smooth muscle contraction so milk is ejected
