Maternal Changes In Pregnancy Flashcards
What are the 3 elements that make up the human blastocyst?
- Inner cell mass: Forms the foetus
- Trophoblast: Forms part of the placenta
- Blastocoel: Fluid filled cavity
When does the endometrial reach their maximum during Uterine receptivity?
- Endometrial changes reach their maximum about 7 days after ovulation.
- The implantation window occurs 6-10 days after the LH spike
When does pre decidualization occur during Uterine receptivity?
Pre decidualization occurs 9-10 days after ovulation, decidual cells cover surface of the uterus
What happens when Decidualization occurs?
- Decidualization occurs if pregnancy occurs, decidual cells are modified and become filled with lipids and glycogen
- Decidua becomes maternal part of the placenta
What does glandular secretions contain?
- Growth factors
- Adhesion molecules
- Nutrients
- Vitamins
- Matrix proteins
- Hormones
What happens at day 7-8 of implantation?
- Blastocyst attaches itself to the surface of the endometrial wall (Decidua basalis)
- Trophoblast cells start to assemble to form a syncytiotrophoblast in order to facilitate invasion of the Decidua basalis
What happens at day 9-11 of implantation?
- Syncytiotrophoblast further invades the Decidua basalis
- By day 11, it’s almost completely buried in the Decidua
What happens at day 12 of implantation?
- Decidual reaction occurs
- High levels of progesterone result in the enlargement and coating of the decidual cells in glycogen and lipid rich fluid
- This fluid is taken up by the syncytiotrophoblast and helps sustain the blastocyst early on before the placenta is formed
What happens at day 14 of implantation?
- Cells of the Syncytiotrophoblast start to protrude out to form tree like structures known as primary villi
- Which see then formed around the blastocyst
- Decidual cells between the primary villi begin to clear out leaving behind spaces known as Lacunae which fill the maternal blood
How is a pregnancy recognised maternally?
- Human chorionic gonadotrophin (hCG) secreted by the syncytiotrophoblast increases rapidly and is the basis of a pregnancy test
- hCG prevents the death of the corpus Luteum so the endometrium is not shed
- The corpus Luteum continues to produce steroids estrogen and progesterone.
- Rapid change in maternal systems in response to luteal and later placental steroids
Describe the different stages of the hormone concentration against weeks of pregnancy graph
- Estrogen is produced from the start (week 0)
- progesterone starts production at 2nd week
- Serum hCG is produced just before the 4th week
Describe the different stages of the hormone concentration against weeks of pregnancy graph (PART 2)
- Serum hCG concentration peaks the highest at week 10
- Estrogen and Progesterone concentration gradually increases
- After week 10, Serum hCG conc decreases rapidly and falls below Estrogen & Progesterone conc at around week 24
- At week 24 Estrogen conc surpasses progesterone conc
What is the order of finish for the hormone concentration against weeks of pregnancy graph
- Estrogen
- Progesterone
- Serum hCG
Where is progesterone synthesised from?
Where is it needed?
- Synthesised directly from cholesterol
- Decidualization (CL)
- Smooth muscle relaxation: Uterine quiescence
- Mineralcorticoid effect: Cardiovascular changes
- Breast development (glands and stroma)
Where is Estrogen synthesised from?
Where is it needed?
- Synthesised from steroids derived from foetal and maternal adrenals
- Development of uterine hypertrophy
- Metabolic changes (insulin resistance)
- Cardiovascular changes
- Increased clotting factor production
- Breast development (glands and stroma)
What is the average total weight gain for a women during pregnancy?
Around 9-13 kg
What factors causes most of this weight gain?
- Foetus and placenta: 5 kg
- Fat and protein: 4.5 kg
- Body water: 1.5kg
- Breasts: 1 kg
- Uterus: 0.5 kg
What would happen if this weight gain is not reached?
- Failure to gain or sudden change requires investigation
- Constant weight monitoring can cause anxiety
How is weight expected to increase during pregnancy?
- Around 2 kg in total for the first 20 weeks
- Then approximately 0.5 kg per week until full term at 40 weeks
- A total of 9-13 kg during the pregnancy
How much does the basal metabolic rate increase by?
- 350 kcal/day mid gestation
- 250 kcal/day late gestation
- 9 calories = 1g fat therefore 40g fat for 350 kcal
- Glucose increases in the maternal circulation in order to cross the placenta
How does glucose in the body change in the first trimester of maternal reserves?
- Pancreatic cells increase in number raising circulating insulin
- So more glucose is taken up into tissues
- Fasting serum glucose decreases
How does glucose in the body change in the second trimester of maternal reserves?
Placental Lactogen causes insulin resistance, ie less glucose into stores and increase in serum glucose.
How does glucose in the body change in the third trimester of maternal reserves?
- Increased glucose level in blood during the 2nd trimester
- Glucose is transported across the placenta at foetal energy stores
- Foetus stores some in liver
How does Estrogen and Progesterone cause total water gain?
- These hormone levels are so high that they act like mineralcorticoids
- Retain more sodium from kidneys thereby increasing blood volume
How does the RAAS system cause total water gain?
- placental renin production.
- Estrogen upregulates angiotensinogen synthesis by liver leading to increased angiotensin II and aldosterone.
- Despite higher ANGII women resistant to AT2 receptor mediated vasoconstriction because progesterone decreases vasosensitivity
How does connective tissues and resetting osmostat cause total water gain?
- Connective tissue and ligaments take on water and become a bit softer
- Resetting osmostat, decreased thirst threshold. Decrease in oncotic pressure (albumin)
In the Maternal blood,
How much does Maternal plasma volume increase by?
How much does Red cell mass increase by?
- Maternal plasma volume: 45% increase
- Red cell mass: 18% increase
How does the Maternal plasma volume content change?
- Increased efficiency of iron absorption from the gut
- Circulating volume increases from 4.5 to 6.0 litres
- Hawmodilution: Apparent anaemia as concentration of Hb falls
How does the Red cell mass content change?
- Increase in white cells and clotting factors
- Blood becomes hypercoagulable
- Increased fibrinogen for placental separation, but increased risk of thrombosis
How does the cardiovascular system change during pregnancy?
Expanding Uterus pushes the heart, causing changes in ECG and heart sounds
How does this cause ECG changes in the cardiovascular system?
Peripheral vasodilation
- Mediated by endothelium dependent factors
- Such as nitric oxide synthesis upregulated by E2
- 20-30% fall in TPR so Cardiac output increases
What does the peripheral vasodilation result in?
Increased Cardiac output
- Increased heart rate (8-10bpm) but primarily stroke volume
- Begins as early as 3 weeks to max 40% at 28 weeks
- BP decreases in 1st 2 trimesters
The increased cardiac output increases blood flow to which blood vessels?
Increased Cardiac output, reduced peripheral resistance and increased flow to:
- Uterus
- Placenta
- Muscle
- Kidney
- Skin
What else happens during this increased cardiac output?
Neoangiogenesis, including extra capillaries in skin to assist heat loss
- Pregnancy characterised by low pressure and high blood volume
Describe how dietary supplementation such as folic acid works
Folic acid -> DNA production causes growth of blood cells which then branches in 3: Uterus, Placenta, Foetus
Why is supplementation needed?
- Deficiency can lead to birth defects eg spina bifida
- Supplementation advised up to 400 ug/day until week 12
- Ideally 3 months before pregnancy
How does the urinary system change during pregnancy?
- Urinary tract -> dilates relaxes -> Increased UTI may persist
- Kidney -> Increased blood flow -> Increased filtration rate -> Increased clearance of creatine, urea & Uric acid
- glucose reabsorption less effective
What does relaxin from the corpus Luteum do?
Stimulates formation of the endothelin which mediates dilation of renal arteries by nitric oxide synthesis
How does Progesterone and VEGF cause resistance?
Cause resistance to angiotensin II mediated vasoconstriction
- leading to further vasodilation and increased renal blood flow and increased GFR
What happens to Cortisol in the foetus?
- Metabolic changes occur such as insulin resistant
- Foetal lung maturity and mineralcorticoid action (aldosterone)
- Increased prostaglandin E2 & Oxytocin production by placenta
What does corticotrophin releasing hormone (CRH) do in the foetus?
- CRH is released into the maternal and foetal circulation by placenta.
- Increases cortisol (positive feedback) and stimulates adrenocorticotrophic hormone (ACTH) & so DHEA in foetal HPA axis
What does corticotrophin releasing hormone (CRH) do in the foetus? (PART 2)
- DHEA is aromatised into estrogen by the placenta
- Increasing E:P ratio and stimulating prostaglandins which activate blood flow, uterine contractions ap& cervical ripening
How does the thyroid gland change during pregnancy?
- Increased production of thyroid hormone to meet increased metabolic demands of pregnancy
- Leads to a risk of gestational thyrotoxicosis
- hCG May act on the TSH receptor
What happens if the individual has a history of Hyperthyroidism?
If the patient has a history of hyperthyroidism such as Graves’ disease:
- They may require endocrine treatment
- This helps to maintain normal function
What tests can be used to indicate hyperthyroidism?
Biochemical tests may indicate hyperthyroidism in pregnancy where in fact the patient is normal (euthyroid).
What are the symptoms of hyperthyroidism?
Symptoms can include a whole list of different factors:
- anxiety, tremor, heat intolerance, palpitations, weight loss or lack of weight gain, goiter, tachycardia, and hyperreflexia but usually associated with persistent vomiting of hyperemesis gravidarum.
What does suppressed TSH and high serum T4 indicate?
Indicate thyrotoxicosis
When does Uterine hypertrophy occur?
- At 12 weeks of gestation, the uterine fungus may be palpated through the abdomen above the symphysis pubis
- Large increase in muscle mass during first 20 weeks (50g – 1000g)
- After this stretching & increases in blood flow; size reaching a peak at 36 weeks.
What is the function of the cervix in general?
To retain the pregnancy
What changes occurs in the cervix during pregnancy?
Increase in vascularity
Tissue softens from 8 weeks
- Changes in connective tissue
- Begins gradual preparation for expansion
Proliferation of glands
- Mucosal layer becomes half of mass
- Great increase in mucus production
- Protective ie anti reflective
What role does prolactin play in pregnancy?
In addition to pituitary production, prolactin is produced by myometrium and placenta during pregnancy in response to high estrogen and progesterone. However, estrogen and progesterone inhibit the stimulatory effects of prolactin on milk production.
The abrupt drop in estrogen and progesterone levels following placental delivery allows high levels of prolactin to induce lactation.
After birth, sucking activates nipple mechanoreceptors signaling the hypothalamus and causing anterior pituitary prolactin secretion
What role does Oxytocin play in pregnancy?
Stretching of uterus and cervix during childbirth causes release of oxytocin which helps with the birth and emotional bonding with the baby.
Suckling stimulus triggers the release of oxytocin from the posterior pituitary gland, which triggers milk ejection.
In what way is oxytocin and prolactin the reverse of eachother?
- Prolactin controls milk production
- Oxytocin causes the Milk ejection reflex
After pregnancy, how does the body return back to normal?
- Dramatic and rapid fall in steroids on delivery of the placenta
- Most endocrine-driven changes return to normal rapidly
- Uterine muscle rapidly loses oedema but contracts slowly: but doesn’t to pre-pregnancy size
- Removal of steroids permits action of raised prolactin on milk production
