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Flashcards in placenta/pregnancy 3 Deck (16):

beta- hCG

(human chorionic gonadotrophin)

produced exclusively by the syncytiotrophoblast of the preimplantation blastocyst and placenta

is detectable in the maternal blood/urine within days of implantation

can be used as an indicator for the health of the pregnancy


functions of hCG

binds to the LH/hCG receptor and thus transmits similar signals to LH

luteal support:
-hCG has strong leutotrophic properties and is importnat in stimulating the production of P4 and E2 by the ovary in first 6-8 weeks of pregnancy
-stops regression of corpus luteum

The corpus luteum doubles in size about a month into pregnancy under the influence of hCG


what causes estrogen and progesterone to be secreted and its effect

corpus luteum secretes E2 and P4 from the signals coming from the placenta in the form of hCG

- prevents menstruation
- maintains endometrium as a decidua


hCG levels in multiple pregnancies

women with multiple pregnancies have increased levels of hCG
- this is because of the increased amount of syncytiotrophoblast in twin pregnancy


other than in multiple pregnancies where else can high levels of hCG be found

trophoblastic tumours
-choriocarcinoma and hydatidiform mole
-also in some testicular tumours


hCG importance in male pregnancies

in having LH-like activity that stimulates testosterone synthesis by the leydig cells of the testis in male fetuses


progesterone in pregnancy and its importance clinically

is synthesised by the syncytiotrophoblast of the placenta

therefore ovaries can be removed without disrupting the pregnancy from the time that the placenta takes over P4 production (instead of the corpus luteum) = 6-10 weeks


functions of progesterone

- maintains uterine quiescence (P4 is a SM relaxant)

- along with E2 it converts the uterine environment to one that is conducive with pregnancy

- P4 receptors are expressed by both glands and stromal cells in the decidua


is the decidua essential for implantation

no, this can be verified by ectopic pregnancies

however it is important for providing nutrients prior to the maternal blood supply


oestrogen changes during pregnancy

theres a 1000 fold increase in E2 during pregnancy


how is oestrogen produced during pregnancy

cholesterol is taken up in the maternal blood and converted into P4 in the syncytiotrophoblasts (placenta). P4 then taken up by the fetal circulation to the fetal adrenals and liver. In those organs androgens are created by 17 alpha hydroxylase. Then shuttled back to the placenta where they're aromatised to estrogens
- (aromatisation occurs in syncytiotrophoblasts)


cardiovascular adaptations during pregnancy (& preeclampsia)

occurs 9-10 weeks gestation

increased CO
-increased SV and pulse rate

reduced peripheral vascular resistance

preeclampsia = higher than 'normal' PVR



maternal hypertension after the 20th week of gestation accompanied by protein in the urine

- affects most maternal organs
- triggered by something from the placenta (only cure is to deliver)
- exaggerated inflammatory response leading to vascular dysfunction
- loss of normal peripheral vascular resistance


apart from haematological changes whats causes cardiovascular changes during pregnancy

angiotensin II is a vasoconstrictor which causes the arterioles to contract and increase BP
- its levels increase in pregnancy
- uteroplacental unit produces RAS

nitric oxide synthetase is increased in pregnancy
-NO causes arterial wall relaxation and dilation


haematological changes during pregnancy and clinical importance

increased BV
- plasma volumes and BV both increase but at different rates

haematocrit declines as plasma volume increases at a higher rate than cell mass

important to remember when taking blood test results from pregnant women that the normal values change for pregnant population


immune system adaptations during pregnancy

fetus is genetically half paternal and half maternal