Physiology of Pregnancy and Lactation Flashcards
what happens 3-5 days after fertilisation
transport of blastocyst into the uterus
what happens 5-8 days after fertilisation
blastocyst attaches to lining of uterus
what does the blastocyst include
inner cells (embryoblast) - which become embryo
outer cells - trophoblast cells, become the placenta
what does the placenta do
produces hormones to maintain pregnancy
trophoblast cells differentiate into syncytiotrophoblasts which invade decide and break down capillaries to form cavities filled with maternal blood
developing embryos sent capiliaries into the syncytiotrophoblast projections to form placental villi
has 2 ways of exchange - respect gases, nutrients, metabolites between mother and foetus
when is the placenta and foetal heart functional by
5th week of pregnancy
what hormone signals the corpus lute to continue to secrete progesterone in pregnancy
HCG (human chorionic gonadotrophin)
what does prolonged progesterone secretion by corpus luteum cause in pregnancy
stimulates decidual cells to concentrate glycogen, protein and lipids
how does the placenta act as the ‘lungs’ for the foetus
gas exchange between oxygen rich maternal blood compared to the foetal circulation
reversible exchange of carbon dioxide from foetus to mother
what 3 factors facilitate the supply of the foetus with oxygen
- foetal Hb (increased ability to cary O2)
- higher Hb concentration
- Bohr effect (fetal carries more oxygen in low pCO2 than in high pCO2)
how does the foetus get water
increase in water exchange across an osmotic gradient up till the 35th week of pregnancy
how do nutrients and electrolytes cross the placenta
can only cross from mother to foetus
glucose passes via simplified transport to the foetus
free diffusion of fatty acids across the placenta
what are teratogens
drugs that cross the placenta and effect the foetus, eg.
tetracycline, carbamazepine, thalidomide
alcohol, nicotine, heroin, coccaine, caffeine
what does HCG do
prevents break down of corpus luteum
effects the testes of male foetus- development of sex organs
what does HPL (human placental lactogen)
produced from week 5
growth hormone like effects
decreases insulin sensitivity
involved in breast development
what does progesterone do in pregnancy
development of decimal cells
decrease of uterus contractility
preparation for lactation
what does oestrogen’s do in pregnancy
enlargement of uterus
breast development
relaxation of ligaments
how should HCG increase in early pregnancy
serum levels should double every 48 hours in a singleton early pregnancy
what changes can you monitor via HCG levels
ectopic pregnancy - static or slow rising
failing pregnancy - falling
ongoing viable pregnancy - doubling or >60% rise
side effects of increased HCG
nausea
vomiting
high levels can occur in:
multiple pregnancy
molar pregnancy
when does HCG start to go down again in normal pregnancy
12-14 weeks
woman starts feeling better - less morning sickness
how much does the mothers cardiac output increase in pregnancy
30-50%
when does cardiac output decrease in pregnancy
last 8 weeks
foetus compressing vena caca
what normal changes can be seen in pregnancy because of raised CO
ECG changes
functional murmurs
heart sounds
what happens to plasma volume in pregnancy
increases proportionally with cardiac output
why is Hb decreased in pregnancy
increased plasma volume causes increased dilution
what happens to iron requirements in pregnancy
increases significantly
iron supplements often needed
what respiratory changes happen in pregnancy
changes occur due to increase progesterone and large uterus decreasing lung function
progesterone lowers CO2 levels
O2 consumption increases to meet metabolic needs to foetus
what happens to the urinary system in pregnancy
GFR and renal plasma flow increases
increased re-absorption of ions and water due to placental steroids and aldosterone
increase of urine formation
how do postural changes in pregnancy cause changes in renal function
decreased in up right position
increased in a supine position (lying flat)
increased in a lateral position during sleep (lying on side)
what is pre-eclampsia
pregnancy induced hypertension and proteinuria
increasing BP since 20th week
kidney function declines, salt and water retention leads to oedema formation
who is pre-eclampsia more common in
pre-existing hypertension diabetes autoimmune disease renal disease family history of pre-eclampsia obesity multiple pregnancy
what is the average weight gain in pregnancy
11kg
what is the pregnancy weight gain from
foetus placenta amniotic fluid extracellular fluid other tissue - fat uterus and breast tissue increase in blood
how many extra calories a day do you need in pregnancy
200
what are the 2 phases of metabolism in pregnancy
1st-20th week - mothers anabolic phase
- anabolic metabolism for mother
- low metabolic needs of foetus
21st-40th week (catabolic phase)
- high metabolic demands of foetus
- accelerated starvation of the mother
what happens in the mothers anabolic phase
Normal or increased sensitivity to insulin
Lower plasmatic glucose level
Lipogenesis, glycogen strokes increase
-growth of breasts, uterus, weight gain
what happens in the mothers catabolic phase
increase in maternal insulin resistance
increased transport of nutrients through placenta
lipolysis
insulin resistance is caused by human placental lactose, cortisol and growth hormone
what nutrients need to be taken in pregnancy
Folic acid - reduces risk of neural tube defects Vitamin D supplements High protein diet, higher energy uptake Iron supplements B-vitamin -erythropoesis
what happens to the uterus towards the end of pregnancy
gets more excitable due to the oestrogen:progesterone ratio falling
oestrogen increases contractility
oxytocin increases contractions
what drugs can be used to induce labour
vaginal prostaglandins
oxytocin
what are Braxton hicks contractions
tightening of uterus
increase towards the end of pregnancy
what causes positive feedback to increase oxytocin release
stretch of the cervix by foetal head
increased oxytocin increases uterine contractions
also increases prostaglandin secretion which again increases contractions
1st stage of labour
cervical dilation
8-24 hours
2nd stage of labour
passage through birth canal (few mins to 120 mins)
what is the 3rd stage of labour
expulsion of placenta
what hormones are involved in producing lactation
prolactin
oxytocin
oestrogen
progesterone
what does oestrogen do for lactation
growth of ductile system
prevents milk production in pregnancy
what does progesterone do for lactation
development of lobule-alveolar system
prevents milk production in pregnancy
what does prolactin do for lactation
stimulates milk production
1-7 days after birth, prolactin induces high milk production
stimulates colostrum (first form of milk produced)
