physiology of pregnancy and lactation Flashcards
what happens at 3-5 days after fertilisation
transport of the blastocyst to the uterus
what happens at 5-8 days after fertilisation
blastocyst attaches to the lining of the uterus
what does the blastocyst turn into
-inner cells develop into embryo
-outer cells burrow into uterine wall and become placenta
when is the placenta (and fetal heart) functional?
5th week of pregnancy
what signals the corpus luteum to continue secreting progesterone
hCG
what does the progesterone do in placental development
stimulates decidual cells to concentrate glycogen, proteins and lipids
how does the placenta work as an atriovenous shunt
-extends villi into uterine wall
-which means nutrients and waste materials can be exchanged between the placenta and uterus
-blood vessels from the embryo devleop in the villi
-there is no direct contact between fetal and maternal blood
what facilitates to supply of oxygen to the fetus by the placenta
-fetal Hb
-higher Hb concentration in fetal blood
-Bohr effect (fetal Hb can carry more oxygen in low pCO2 than in high pCO2)
what does hCG do in pregnancy
-prevents inovulation of corpus luteum
-development of sex organs in male fetus
when is HCS (human chorionic somatomammotropin)/human placental lactogen produced
around week 5 of pregnancy
what does human placental lactogen do
- Growth hormone-like effects - protein tissue formation
- Decreases insulin sensitivity in mother - more glucose for the fetus
- Involved in breast development
when do hCG levels drop off
fall from 12-14 weeks
side effects of. hCG
nausea
vomiting
hCG in an ectopic pregnancy
static or slow rising
hCG in a failing pregnancy
falling
hCG in an ongoing viable pregnancy
doubling or >60% rise
what does progesterone do in pregnancy
- Development of decidual cells
- Decreases uterus contractility
- Preparation for lactation
what does estrogen do in pregnancy
- Enlargement of uterus
- Breast development
- Relaxation of ligaments
cardiovascular changes in pregnancy
-increase in cardiac output
-functional murmurs
-heart sounds
-HR increases
-BP drops during second trimester
ECG changes in pregnancy
-relative sinus tachycardia
-slight left axis deviation
-inverted or flattened T waves
-Q-wave
-atrial and ventricular ectopic beats more common
haematological changes in pregnancy
- Plasma volume increases proportionally with cardiac output
- Erythropoesis increases, thus Hb is decreased by dilution (decreases blood viscosity)
- Iron requirements increase significantly - iron supplements needed
what do lung function changes happen due to
partly due to progesterone increases and partly because of the enlarging uterus interfering with lung function
what are the respiratory changes during pregnancy
-lower CO2 levels
-O2 consumption increases
-respiratory rate increases
urinary system changes in pregnancy
-GFR and renal plasma flow increases
-increased reabsorption of ions and water
-slight increase in urine formation
coagulation state in pregnancy
hypercoaguable state
-reduces risk of haemorrhage during and after delivery
-increased risk of venous thromboembolism
average maternal weight gain
11kg
when is the mother’s anabolic rate
1st-20th week
-small nutritional demands of the conceptus
when is the mother’s catabolic phase
21-40 weeks
-high metabolic demands of the fetus
what is insulin resistance caused by in pregnancy
HPL, cortisol and growth hormone
in what phase does insulin resistance happen
catabolic phase
nutritional needs in pregnancy
-folic acid
-vit D supplements
-high protein diet
-iron supplements
-B vitamins
why do mothers take folic acid
reduces risk of neural tube defects
hormonal changes in parturition
-estrogen/progesterone ratio alters
-prostaglandins produced by placenta
-oxytocin released from posterior pituitary
what does progesterone do in parturition
inhibits contractility
what does estrogen do in parturition
increases contractility
what does oxytocin do in parturition
increases contractions and excitability
what happens at the onset of labour
- Braxton Hicks contractions increase towards the end of pregnancy
- Cervical rupening
- Stretch of the cervix by fetal head increases contractility
- Cervical stretching also causes further oxytocin release
- Strong uterine contraction and pain from the birth canal cause neurogenic reflexes from spinal cord that induce intense abdominal muscle contractions
how is labour initiated
what is the first stage of labour
cervical dilation
-8-24 hours
what is the second stage of labour
passage of fetus through birth canal
-few min to 120 mins
what is the third stage of labour
expulsion of placenta
estrogen and progesterone role in inhibiting milk production
estrogen - growth of ductile system
progesterone - development of lobule-alveolar system
what hormone stimulates milk production
prolactin
what hormone is responsible for the ‘milk let down reflex’
oxytocin
feedback loop for milk production and release
what is the milk let down reflex
