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Y2S2M3 > Endocrinology of Pregnancy and Parturition > Flashcards

Endocrinology of Pregnancy and Parturition Flashcards

1
Q

How do the hormones of the mother and fetus interplay?

A

From fertilisation, the early embryo influences the mother. Both produce hormones for communication, allowing maternal recognition and support of pregnancy

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2
Q

Outline the female uterine development in a fertilised cycle.

A

The ovarian follicle develops and releases the egg during ovulation, which is secondary to an LH surge. The blastocyst implants and differentiates into a trophoblast structure. The corpus luteum forms after egg release, supporting early pregnancy by secreting progesterone, oestrogen, and relaxin.

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3
Q

What is HCG?

A

HCG is a glycoprotein with alpha and beta subunits. The alpha subunit is identical to that of LH, FSH, and TSH.

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4
Q

Where does HCG act and what does it do?

A

HCG acts on LH receptors.

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5
Q

What are the functions of HCG?

A

Maintains corpus luteum and progesterone production, stimulates DHEA production in the fetal adrenal gland, and induces masculinisation in males. HCG is a marker for viable pregnancy, doubling every 48 hours.

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6
Q

What secretes HCG and when is it released?

A

HCG is secreted by the syncytiotrophoblast layer of the implanting blastocyst 6-7 days post-fertilisation and released into maternal circulation.

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7
Q

How can HCG be useful in monitoring pregnancy?

A

A decrease in blood HCG correlates with a decrease in 17-hydroxyprogesterone from the corpus luteum, indicating a potential loss of pregnancy.

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8
Q

How do urine pregnancy tests work?

A

HCG is excreted by the kidneys, allowing for urine pregnancy tests for beta subunit HCG, though false readings can occur.

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9
Q

What is progesterone?

A

Progesterone is a key pregnancy hormone essential for the continuation of pregnancy.

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10
Q

What happens if you block progesterone?

A

Removal of the ovary or administration of a progesterone inhibitor results in pregnancy loss.

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11
Q

What secretes progesterone?

A

Initially secreted by the corpus luteum, then produced from cholesterol by syncytiotrophoblast, with placental secretion taking over between 6-8 weeks.

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12
Q

What are the functions of progesterone?

A

Maintains the decidua, relaxes the myometrium, resets respiratory centre, increases body temperature, increases protein breakdown for fetal amino acids, and promotes breast alveolar cell proliferation.

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13
Q

When do miscarriages take place?

A

When there is a mismatch between the corpus luteum and placenta shift.

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14
Q

When do progesterone levels fall and how does this affect the myometrium?

A

Progesterone levels fall at the end of pregnancy, leading to myometrium contractions and labor.

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15
Q

What are the effects of progesterone on the endometrium?

A

Decidual transformation, immune modulation, and negative regulation of human placental lactogen.

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16
Q

What are the three types of oestrogen and when do they predominate?

A

Oestrone (E1) predominates in menopause, Oestradiol (E2) regulates menstruation, and Oestriol (E3) is specific to pregnancy.

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17
Q

What is the main source of oestrogen in pregnancy?

A

The placenta and fetal liver, with Oestradiol (E2) being the most potent.

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18
Q

Describe the levels of oestrogen throughout pregnancy.

A

Oestrogen levels rise throughout pregnancy, with Oestriol (E3) predominating and Oestradiol produced towards term.

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19
Q

How do circulating oestrogens not necessarily influence the fetus?

A

Circulating hormones are bound to carrier proteins and sulphated, rendering them inactive until deconjugated in the placenta.

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20
Q

What are the key roles of oestrogen following implantation?

A

Vascular changes, increased contractile associated proteins, and metabolic changes that influence maternal physiology.

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21
Q

Describe the secretion of placental growth hormone (PGH).

A

Secretion starts from 15-20 weeks, is non-pulsatile, and correlates with placental size.

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22
Q

What is the role of placental growth hormone (PGH)?

A

Modifies receptors for glucose transport to the fetus and stimulates maternal gluconeogenesis and lipolysis.

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23
Q

How is human placental lactogen (hPL) secreted?

A

Produced by syncytiotrophoblasts, rising as hCG falls, with large amounts in maternal blood but little reaching the fetus.

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24
Q

What is the function of hPL?

A

Aids in mammary gland development, fetal nutrition, and increases maternal insulin resistance.

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25
What are the clinical implications of hPL?
Gestational diabetes in mothers, increased IGF1 in the liver, and mobilization of maternal fatty acids for fetal development.
26
What is Relaxin?
Relaxin is a peptide hormone.
27
What is the source of Relaxin?
Primarily produced by the corpus luteum in both pregnant and non-pregnant states.
28
How do Relaxin levels fluctuate?
Levels rise in the first trimester, peak at 14 weeks, and are produced by endometrial decidua and placenta.
29
What is the role of Relaxin?
Increases cardiac output, arterial compliance, renal blood flow, and relaxes pelvic ligaments.
30
What is the source of Prolactin?
Produced by lactotrophs in the anterior pituitary.
31
Describe the fluctuation of Prolactin during pregnancy.
Prolactin levels rise during pregnancy, increasing tenfold in preparation for milk production.
32
What is the role of Prolactin?
Prepares breasts for lactation, aids in lung maturation for the baby, and stimulates milk biosynthesis.
33
What stimulates Prolactin release?
Oestrogen stimulates release by lactotroph cells, with low levels from decidua entering amniotic fluid.
34
What is the position of the fetus prior to birth?
The fetus lies head first within the fetal membranes in the uterus, retained by the cervix.
35
What stimulates release by lactotroph cells?
Oestrogen stimulates release by lactotroph cells and low level PRL from decidua.
36
Where does dPRL enter?
dPRL enters amniotic fluid.
37
What is the position of the fetus prior to birth?
The fetus lies within fetal membranes in the uterus retained by the cervix, head first within 37-40 weeks, and will drop when it comes to the point of parturition.
38
What are the stages of parturition?
1. Contractions begin, dilation and shortening/effacement of cervix. 2. Full dilation of cervix and delivery of baby. 3. Delivery of placenta.
39
What are the NICE guidelines for intrapartum care?
Labour consists of a latent phase (up to 3 cm) and an active phase (3-10 cm).
40
Define nulliparous and parous woman.
Nulliparous = woman never been pregnant; Parous = woman has previously been pregnant.
41
What are the key mediators of parturition?
Increase in oestrogen:progesterone activity ratio, prostaglandins (PGF2α, PGE2), and oxytocin.
42
What 3 key changes does parturition require?
1. Initiating signal (increased maternal/fetal corticosteroids). 2. Coordinated contraction of uterine myometrium smooth muscle. 3. Cervical softening/ripening & dilatation.
43
What is myometrial contractility?
Myometrium remains quiescent during pregnancy due to progesterone suppressing contractility. At term, oestrogen:progesterone ratio increases, leading to myometrium contraction.
44
Which hormones regulate parturition?
Key hormones are progesterone and oestrogen. Progesterone suppresses contractions, and its fall initiates myometrial contractions.
45
How do progesterone levels following labour vary amongst different mammals?
Labour is preceded by a fall in serum progesterone, except in humans and guinea pigs where the fall occurs afterwards.
46
What is Corticotropin-releasing hormone (CRH)?
A precursor of ACTH/Corticotropin produced in response to stress.
47
Describe the levels of CRH throughout pregnancy.
CRH activity increases in primate pregnancies prior to parturition, mostly produced by the placenta.
48
What does CRH do?
Stimulates corticosteroid production from the adrenals, increasing glucocorticoids/cortisol levels.
49
What is the fetus's endocrine contribution to the initiation of labour?
Placental CRH increases with gestation, resulting in DHEAS increasing via fetal adrenal gland, which is converted to oestradiol in the placenta.
50
What does the increasing oestrogen:progesterone ratio promote at term?
Promotes phospholipase A2 activation and local arachidonic acid release.
51
What promotes prostaglandin release?
CRH promotes prostaglandin release.
52
When does cervical ripening/softening occur?
Ripens days/weeks preceding birth, with PGE2, relaxin, and NO contributing.
53
What is PGE2 used for clinically?
Indications include labour and abortion.
54
What is cervical effacement/remodelling?
Cervix becomes thinner, shorter, softer, and moves from back to front due to collagen fibre loosening and increased inflammatory cells.
55
What is oxytocin?
A nonapeptide produced by the neurohypophysis and released by the posterior pituitary.
56
What stimulates oxytocin synthesis?
Oestrogens and tactile stimulation of the uterine cervix.
57
What does oxytocin do?
Lowers the excitation threshold of the myometrial muscle cell.
58
What should be administered if labour begins but doesn’t progress?
Exogenous oxytocin can be given to increase strength and length of contractions.
59
What is the anatomy of the breasts?
15-20 lobes consisting of lobules of alveoli, blood vessels, and lactiferous ducts.
60
Outline hormonal changes that enable lactation.
At birth, progesterone and oestrogen drop significantly, while prolactin levels start to fall but are still present.
61
What are the different phases of milk production?
Colostrum (higher protein, low fat), transitional phase, and full milk production (higher in fat and lactose).
62
Summary of what the hormones do in lactation.
Oestrogen increases size and number of ducts; progesterone increases alveolar cells but inhibits prolactin; hPL stimulates acinar glands; prolactin promotes milk production; oxytocin promotes milk ejection reflex.
63
What promotes prolactin secretion?
Suckling sends messages to the anterior pituitary to release prolactin.
64
What promotes prolactin secretion?
Vasointestinal peptide (VIP) and TRH.
65
What inhibits prolactin secretion?
Dopamine agonists inhibit prolactin secretion. ## Footnote These drugs are used when a woman may have lost her baby to stop milk production.
66
What is the milk ejection reflex (let down)?
The expulsion of breast milk comes via the oxytocin pathway. ## Footnote Nipple stimulation by neonatal sucking leads to the release of oxytocin, which stimulates breast myoepithelial cell contractility, resulting in milk release from alveoli and increased ductal flow to the nipples. It can also promote uterine contractility.
67
What are the advantages of breastfeeding for mum and baby?
Advantages of breastfeeding include nutritional benefits for the baby and health benefits for the mother.

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