Physiology of Pregnancy Flashcards
After fertilisation, the cells of the pre-embryo divide and differentiate into what as it travels down the fallopian tube to the uterus?
Blastocyst
What does the blastocyst become known as once it implants in the endometrium?
Embryo
The outer membranes of the blastocyst develop to form what?
The amniotic sac and placenta
After fertilisation, when does implantation usually occur?
Between days 6-10
An embryo becomes a foetus after how long?
8 weeks
What period of time is defined as the first trimester of pregnancy?
Conception to week 12
What period of time is defined as the second trimester of pregnancy?
Weeks 13 to 27
What period of time is defined as the third trimester of pregnancy?
Week 28 to delivery
What structure provides nutrients for the growing embryo until the placenta is established?
Yolk sac
What is a normal volume of amniotic fluid by late pregnancy?
900-1000mls
The placenta (and the foetal heart) is generally functional by when?
Week 5
Is there ever any direct contact between the foetal and maternal blood in pregnancy?
No
What hormone is responsible for preventing the regression of the corpus luteum in early pregnancy?
Beta HCG
What hormone is responsible for ensuring the endometrium is not shed in early pregnancy?
Progesterone
What hormones are secreted by the placenta?
Oestrogen and progesterone
What happens to the diastolic blood pressure in pregnancy?
Drops in the first two trimesters, returns to pre-pregnancy level in the third trimester
What happens to peripheral vascular resistance in pregnancy?
Decreased
What happens to the cardiac output in pregnancy?
Increases up to 24 weeks, decreases in the last 8 weeks, increases again in labour
If pregnancy causes the cardiac output to rise, this means that what other two variables must also rise?
Heart rate and stroke volume
What happens to the plasma volume in pregnancy?
Increases by 50%
What happens to erythropoiesis in pregnancy?
Increases by 25%
What happens to haemoglobin concentration in pregnancy?
Decreases (up to 20% would be considered normal)
What effect does pregnancy have on coagulation?
Produces a hyper-coagulable state
What happens to the platelet count in pregnancy?
Decreases
What happens to the WCC and ESR in pregnancy?
Increase
What hormone is most responsible for the changes in the respiratory system that are seen during pregnancy?
Progesterone
What happens to the respiratory rate in pregnancy?
Increased
What happens to the tidal and minute volume in pregnancy?
Increased
What happens to the pCO2 in pregnancy?
Decreased
What happens to the vital capacity in pregnancy?
No change
What happens to the PO2 in pregnancy?
No change
What happens to the O2 consumption in pregnancy?
Increases by 20%
What happens to GFR and renal plasma flow in pregnancy?
Increased
What happens to ALP in pregnancy?
Increases by 50%
What happens to calcium requirements in pregnancy?
Increased
What happens to serum levels of calcium and phosphate in pregnancy?
Decreased
What is the average weight gain in pregnancy?
10-11kg
By the third trimester, how many extra calories per day should be ingested by a pregnant mother?
250-300
