Maternal Adaptations to Pregnancy Flashcards
How do satiety/motility/absorption mechanisms change in pregnancy?
- Positive energy balance required
- Therefore, increased hunger, and decreased sensitivity of signals from gastric stretch receptors and leptin (what is this?)
- Intestinal absorption of nutrients is also likely to increase in response to slower movement of food through GIT
- What do you think would happen to energy usage from the baseline metabolism in this setting?
How does insulin metabolism change in pregnancy? Link this to a common pathology.
How does this affect energy stores?
- Placental hormones cause diabetes
- At the same time, increased proliferation of beta cells causes increased insulin levels
- This causes increased fat stores
- In cases where beta cells cannot proliferate fast enough to produce enough insulin, gestational diabetes occurs
Why does insulin resistance need to occur in pregnancy?
- Glucose moves across the placenta via faciliated diffusion
- This means the mother conc must be higher than the fetuses conc, otherwise no diffusion
- To sure this balance remains stable, insulin resistance occursa
Why do pregnant women need to develop fat stores in early pregnancy? (link everything together)
- In late pregnancy, placental hormones induce insulin resistance to ensure the fetus gets glucose (how?)
- When the body is insulin resistant, we need to source energy from elsewhere, such as lipolysis
- Therefore, we need increased fat stores to prepare
Cholesterol is used by the placenta to synthesise?
Steroid hormones
What happens to cardiovascular function in pregnancy? Why does this occur? Provide a renal link
- Stroke volume and heart rate increase, leading to a 30-50% increase in total cardiac output
- This occurs to increase perfusion of placenta, and to support the body’s increased metabolic needs
- This is alongside RAAS upregulation, which prompts increased retention of water (and thus ↑plasma volume)
How does blood pressure change across pregnancy? Why does this occur?
- ↑ ostrogen causes ↑ nitric oxide
- This vasodilation causes ↓ blood pressure
- Over time, RAAS upregulation causes ↑ blood volume, and thus ↑ BP
- Therefore, BP first decreases, then re-increases, forming a U shape
What renal adaptations occur during pregnancy? Why?
- We need more blood volume to peruse placenta etc
To do this, we have:
- Significant increase in renal perfusion in response to vasodilation from ↑NO (why doesn’t filtration pressure ↑?)
- Increased GFR in response to this, leaidng ot lower creatinine and urea
- Increased reabsorption of sodium and water (oestrogen upregulates RAAS)
- Dilation of urinary collecting ducts (which predisposes to what pathology?)
Describe structural respiratory changes that occur during pregnancy
- Diagphragm displaced superiorly 4-6cm by expanding uterus
- Rib cage expands to compensate (mostly transversely)
Describe functional resp changes during pregnancy? What concentration gradient is at the heart of this?
- Fundamentally, we need higher maternal PaO2, and lower PaCO2, so the baby can “breathe”
- To get higher O2, we increase tidal volume and resp rate
- Progesterone causes increases susceptibility of the brain to CO2, which helps drive the above changes
- Functional residual capacity decreases (what is this?)
- Decreased CO2 also results in mild ______osis (which?)
What are some changes that are likely to facilitate increased absorption of nutrients (macro/micro) during pregnancy?
- Increased size/weight of small intestine
- Progesterone slows motility of small intestine
The function of HCG in pregnancy is… It is secreted from …
- Secreted from syncitiotrophoblast
- Function is to sustain the corpus luteum (stop it from becoming “ albicans) until the placenta can take over the function of producing progesterone
List three functions of progesterone in pregnanacy
- Increases sensitivity of brainstem resp centre to CO2 (why is this crucial?)
- Suppresses unwanted myometrial contractions
- Promotes immune tolerance (which 2 cell types?)
Alongside progesterone, oestrogens also increase during pregnancy.
Now, true or false: the human placenta cannot make oestrogens, and must import them entirely from the body of the mother
- False
- The placenta can perform some (but not all) of the synthesis
- The precursors are made in the fetal adrenal glands
What are some roles of oestrogens in pregnancy
- Vasodilators
- Increase P4 secretion
- Stimulates RAAS, leading to increased ______ volume in blood
- Promote mammary gland development (link this to an undesirable condition in males)
Function of GH and GH-variant in pregnancy (which is produced where?)
- GH is produced in the anterior pituitary, GH-V is produced in the placenta (latter is more dominant in late pregnancy)
- Function is to induce insulin resistance (why?) and to shift metabolism towards lipids and away from glucose (why?)
- Memory cue -> increases fetal growth @ expense of mother
Where is human Placental Lactogen (hPL) produced? What is its function in pregnancy?
- Produced in syncitiotrophoblast (just like hCG; similar name)
- Functions are: increased beta cell proliferation/insulin secretion, mammary gland development, and fetal growth
(Basically, securing glucose and breast milk supply for baby, then directly affecting growth as well)
Function so prolactin in pregnancy? Which hormone is this very similar to?
- Very similar to human Placental Lactogen (hence -lact; close name for close function)
- Job is ↑ insulin, ↑ beta cell proliferation, and ↑ mammary gland development
- Breast growth/preparation for lactation
(again, locking down the food supply)
Source/function of relaxin in pregnancy
- Comes from corpus luteum and placenta
- Job is relaxation of ligaments/pelvic floor muscles, as well as systemic vasodilation (including kidneys -> ↑ GFR)
- Also causes cervical softening
(Corpus luteum has finished its job of being the main P4 producer, and is now relaxin’)
Function of leptin in pregnancy. How is this different from normal?
- Leptin allows placental nutrient exchange; important for growth of fetus
- Central leptin intolerance allows mothers to keep eating and override regular satiety mechanisms, allowing for increased fat stores
What factors affect how much extra someone needs to eat during pregnancy?
- Older (the older they are, the less extra food needed)
- Weight (if obese, don’t have to each as much extra)
- Physical activity (if inactive, don’t have to eat as much extra)
How many extra kilojoules should a woman eat in the 2nd and 3rd trimester (respectively)?
2nd: +1400kJ
3rd: +1900kJ
What foods/nutrient types to limit during pregnancy?
- Sat fats
- Added sugar
- Added salt
- Alcohol
Describe altered macromolecule requirements in pregnancy, and describe one supplement that is therefore important
- Protein: important for building new tissues/hormoens
- Carbs: good energy, but can contribute to fetal macrosomia
- Essential fatty acids: important for growth/CNS development, but can are depleted. Therefore supplement omega 3.
List micronutrients that are important during pregnancy
- Folate
- Iron
- Vitamin C
- Calcium
- Vitamin D
- Iodine
These two (socially acceptable) drugs should be minimisedc/eliminated in pregnancy
- Alcohol
- Caffeine (weaker evidence, but still)
What are the only two micronutrient supplements recommended during pregnancy?
- Iodine
- Folic acid
(Only others recommended may be iron, if lost)
Which food groups contain iodine?
- Dairy
- Eggs
- Seafood
- Bread w/ iodine-fortified salt
Which food groups contain folate?
- Leafy greens
- Fortified bread
- Legumes/eggs
