Pregnancy physiology Flashcards
What happens the breasts throughout pregnancy?
> Increased size and vascularity – warm tense and tender
Increased pigmentation of the areola and nipple
Secondary areola appears
Montgomery tubercules appear on the areola
Colostrum like fluid can be expressed from the end of the 3rd month
What happens the CVS throughout pregnancy?
> Significant changes occur early in first trimester
Increased circulating blood volume -50-70% of non pregnant
Systemic vascular resistance falls – maximal at 20-32 wks
Increased blood flow
Increased cardiac output (40%), stroke volume increases (SVxHR= CO)
Increased heart rate
In supine position – 25%reduction in cardiac output
Increased O2 consumption
What happens the CVS at 20-32 wks pregnancy?
Systemic vascular resistance falls maximally between this point
What happens the circulating blood volume during pregnancy?
Increases 50-70%
What happens blood flow during pregnancy?
Increased blood flow
What happens the cardiac output during pregnancy?
Increased CO due to an increase in both stroke volume and hear rate
What happens the O2 consumption during pregnancy?
Increased O2 consumption
Intrapartum cardiovascular changes?
> Autotransfusion of contractions
Pain – increasing catecholamines
CO increases by 10% in labour and by 80% in 1st post delivery hour
Postpartum cardiovascular changes?
> Return to normal by 3 months (mostly)
Blood volume decreases by 10% 3 days post delivery
BP initially falls then increases again days 3-7(pre preg levels by 6 wks)
SVR increase over first 2 wks to 30% above delivery levels
HR returns to pre pregnancy over 2 weeks
CO increases by up to 80% 1st hr post delivery then continues to fall over the next 24 weeks
Postpartum cardiovascular changes - Blood volume?
Decrease by 10% 3 days post delivery
Postpartum cardiovascular changes - BP?
> BP initially falls then increases again days 3-7
> Pre pregnancy levels by 6 wks)
Postpartum cardiovascular changes - SVR?
SVR increase over first 2 wks to 30% above delivery levels
How long does it take for the HR to return to normal following delivery?
Returns to pre pregnancy rate over 2 weeks post delivery
Postpartum cardiovascular changes - CO?
CO increases by up to 80% 1st hr post delivery then continues to fall over the next 24 weeks
Respiratory changes during pregnancy?
> Significant increase in oxygen demand (20%) > 40-50% increase in minute ventilation > Increased respiratory rate > Increased tidal volume > Decreased functional residual capacity > PEFR and FEV1 unchanged > PCO2 ↓
Respiratory changes during pregnancy - Oxygen demand?
Significant increase in oxygen demand (20%)
Respiratory changes during pregnancy - minute ventilation?
40-50% increase
Respiratory changes during pregnancy - Respiratory rate?
Increased RR
Respiratory changes during pregnancy - functional residual capacity?
Decreased
Respiratory changes during pregnancy - PEFR and FEV1?
No change
Respiratory changes during pregnancy - PCO2?
PCO2 decreased
Renal system changes during pregnancy?
> Dramatic dilatation of the urinary collecting system – more pronounced on right
Increased renal plasma flow – 60-80% by end of second trimester
GFR ↑ and creatinine clearance increases by up to 50%
Protein excretion increased
Microscopic haematuria may be present
80% women develop oedema
Glycosuria common
Urate ↑ with increasing gestation
Urea ↓, creatinine ↓
Which side has a more pronounced dilation of the urinary collecting system during pregnancy?
The right side
By the end of the second trimester what has happened to the renal plasma flow?
Increase renal plasma flow rate - 60-80% by end of the second trimester
Renal system changes during pregnancy - Glomerular flow rate? What effect does the have on creatinine clearance?
GFR is increased and as a result creatinine clearance goes up by 50%
Renal system changes during pregnancy - protein excretion?
Increased
Renal system changes during pregnancy - Haematuria, glycosuria?
Microscopic haematuria and glycosuria may be present
Renal system changes during pregnancy - urate levels?
Urate increases with increasing gestation
Renal system changes during pregnancy - Urea and creatinine?
Both urea and creatinine decrease
Haematological changes during pregnancy?
> Plasma volume increases cf birthweight > ↓ hg, hcrit, rcc > No change MCV nor MCHC > ↓ platelet count > 2-3 fold increase in requirement for iron > 10 -20 fold increase in folate requirements > WCC increases > Hypercoaguable
Haematological changes during pregnancy - Plasma volume?
Increase
Haematological changes during pregnancy - Haemoglobin, Haematocrit?
Decrease
Haematological changes during pregnancy - platelet count?
Decrease
Haematological changes during pregnancy - Iron requirement?
2-3 fold increase in requirement of iron
Haematological changes during pregnancy - White cell count?
WCC increases
Haematological changes during pregnancy - Coagulability?
Hyper-coagulable
Lab value changes during pregnancy - Hg?
Decrease in Hg
Lab value changes during pregnancy - WCC?
Increase in WCC
Lab value changes during pregnancy - platelets?
Decrease or normal platelet
Lab value changes during pregnancy - CRP?
Normal CRP
Lab value changes during pregnancy - ESR?
Increase ESR
Lab value changes during pregnancy - Urea?
Decrease Urea
Lab value changes during pregnancy - Creatinine?
Decrease in creatinine
Lab value changes during pregnancy - Urate?
Decrease but increases with gestation
Lab value changes during pregnancy - 24hr protein?
Increases
Lab value changes during pregnancy - Total protein?
Decreases
Lab value changes during pregnancy - Albumin?
Decreases
Lab value changes during pregnancy - AST/ALT/GGt?
Decreases or stays normal
Lab value changes during pregnancy - Alk phosphate?
Increases a lot
Lab value changes during pregnancy - Bile acids?
Normal
Lab value changes during pregnancy - D dimer?
Increases
In pregnancy what rescues the corpus luteum from regressing?
The production of human chorionic gonadrotropin (HCG), which is produced by the placenta
What happens to oestrogen throughout pregnancy?
Increases
What happens to progesterone throughout pregnancy?
Increases
What is the role of the increasing oestrogen and progesterone in pregnancy?
1) Maintain endometrium
2) Inhibits FSH and LH release thus inhibiting follicular development
3) Stimulates breast development
What produces the estradiol and progesterone during the first trimester? What stimulates this?
The corpus luteum is responsible for the production of estradiol and progesterone during the first trimester.
The placental HCG stimulates the corpus luteum
When does HCG levels peak?
By week 9 and then begin to decrease
During the second and third trimester what produces the progesterone?
The placenta
During the second and third trimester what produces the oestrogen?
An interplay between:
1) The fetal adrenal cortex which produces DHEA-S, which is hydroxylated in the faetal liver
2) Placenta process this removing sulphate and aromatising to oestrogens
What is the action of oestrogen on the anterior pituitary throughout pregnancy?
1) Negative feedback on the release of LH and FSH inhibiting ovarian follicular development
2) Progressively stimulating the release of prolactin
Why does lactation not occur throughout pregnancy even though levels of prolactin steadily increase?
The high levels of oestrogen and progesterone block the action of prolactin on the breast
Why does lactation rapidly occur following birth?
There is a dramatic decrease in the oestrogen and progesterone levels
How is lactation maintained after birth?
Suckling, which stimulates both oxytocin and prolactin secretion
Why does lactation inhibit another pregnancy?
Lactation inhibits ovulation because prolactin:
1) Inhibits the hypothalamic GnRH secretion
2) Inhibits the action of GnRH on the anterior pituitary, thus inhibiting LH and FSH secretion
3) Antagonizes the action of LH and FSH on the ovaries
As a result ovarian follicular development cannot occur
