Maternal Adaptations to Pregnancy

Question 1

why does female body undergo remarkable physiological adaptations when pregnant

Answer 1

to support developing foetus

Question 2

what plays a crucial role in mediating the bodily adaptations to pregnancy

Answer 2

maternal hormones

Question 3

what adaptations are involved during pregnancy

Answer 3

• cardiovascular shifts
• respiratory modifications
• metabolism alterations

Question 4

what changes in pregnancy make nutritional deficiencies a risk, who can this impact during pregnancy

Answer 4

• increased macronutrient and micronutrient demands to support mother and developing foetus
• nutritional deficiencies during pregnancy can have adverse effects on maternal and foetal health

Question 5

describe cardiovascular maternal adaptations and why they are occurring

Answer 5

• increase in plasma volume and cardiac output
• to supply blood to placental vascular bed & increase supply to maternal organs to support extra work they do during pregnancy

Question 6

[renal adaptations] maternal kidney must adapt during pregnancy. what role does it have

Answer 6

• clearance of waste for foetus and for maternal organs that have increased workload (ie/ more waste)

Question 7

[renal adaptations] list the renal adaptations (adaptations of kidney) during pregnancy

Answer 7

• increase renal blood flow
• increase renal size
• increased glomerular filtration rate (GFR)
• increased reabsorption of sodium
• dilation of urinary collecting ducts

Question 8

[renal adaptations] describe why there is increased renal blood flow

Answer 8

• due to increasing relaxin in circulation
• induces nitric oxide release
• causes vasodilation of renal blood vessels

Question 9

[renal adaptations] describe when and how much renal blood flow increases

Answer 9

• increases early in pregnancy
• increases ~80% by end of first trimester

Question 10

[renal adaptations] why doesn’t glomerular pressure increase with the increase in renal blood flow

Answer 10

• because afferent and efferent arterioles dilate

Question 11

[renal adaptations] why does renal size increase

Answer 11

• since there is greater blood flow into kidney

Question 12

[renal adaptations] when and by how much does renal size increase

Answer 12

• peaks mid-pregnancy
• by 1-1.5cm

Question 13

what is glomerular filtration rate (GFR)

Answer 13

measure of how well kidneys are filtering your blood
- kidneys filter blood by removing waste and extra water to make urine
measure how well kidneys functioning

Question 14

[renal adaptations] when does glomerular filtration rate (GFR) increase and by how much

Answer 14

• increases quickly during pregnancy (within first trimester)
• by 40-50%

Question 15

[renal adaptations] what does elevated GFR result in lower serum concentrations of (2)

Answer 15

• urea
• creatinine

Question 16

[renal adaptations] what does increased GFR often do to renally-cleared medications & what does this depend on

Answer 16

• increases elimination (20-65%)
• reduced half-lives (time it takes for concentration in body of that drug to be reduced by exactly half)
• but effect depends on whether reabsorption in distal tubules also changes which varies between drugs

Question 17

[renal adaptations] why does reabsorption of sodium in distal tubules increase

Answer 17

• due to elevated aldosterone

Question 18

[renal adaptations] how does elevated aldosterone lead to increased reabsorption of sodium in distal tubules (less sodium in urine)

Answer 18

• actions of aldosterone contribute to water and sodium retention in pregnancy
  (aldosterone leads to incr sodium resorption from urine back into bloodstream -> osmotic gradient -> hence water follows out of renal tubules into bloodstream)

Question 19

[renal adaptations] increased water and sodium retention in pregnancy leads to (from incr reabsorption of sodium)

Answer 19

• increase in total body water

Question 20

[renal adaptations] what does increase in total body water result in (from incr reabsorption of sodium)

Answer 20

• increase in plasma volume
• provides water in foetus, placenta, amniotic fluid

Question 21

[renal adaptations] what can increased plasma volume do (from incr sodium reabsorption)

Answer 21

• can decrease circulating concentrations of compounds that are carried in plasma eg/ some drugs and hormones

Question 22

describe amniotic fluid is and its function

Answer 22

• fluid surrounding developing foetus in utero
• formed from mother’s plasma (fluid part of blood)
• functions as: cushion for growing foetus; facilitate exchange of nutrients, water, biochemical products between mother and foetus
• helps protect baby, help support development

Question 23

(fluid surrounding foetus in uteruo) what causes dilation of urinary collecting ducts

Answer 23

• due to smooth muscle relaxation
• induced by progesterone and relaxin (both released during pregnancy)

Question 24

what is relaxin

Answer 24

• reproductive hormone produced by ovaries (corpus luteum) and placenta
• helps to relax muscles, joints, ligaments during pregnancy to help body stretch
• also helps body prepare for delivery by loosening muscles and ligaments in pelvis
• relaxin is made during normal menstrual cycle
• relaxin functions: relax uterus; prepare endometrium for implantation; prevent contractions
• if conception not occur, levels go down until next menstrual cycle
• if conception occurs, relaxin stays high & continues to rise throughout first trimester
• relaxin rises more in luteal phase
• ovaries produce relaxin in normal menstrual cycle (from corpus luteum) during luteal phase; if become pregnant, placenta will also begin to produce & relaxin levels conitnue to rise throughout first trimester
• in body at low levels during follicular phase, until around ovulation when starts to rise (since corpus luteum formed at ovulation?)
• relaxin production will soar if become pregnant
• relaxin levels will peak around end of first trimester (12wks)

Question 25

list the clinical consequences of renal adaptations and growth of uterus during pregnancy

Answer 25

- risk of UTI - glucosuria (glucose in urine) and proteinuria (protein in urine) - increased frequency and urgency of urination

Question 26

[renal adaptations] why does risk of UTI increase during pregnancy

Answer 26

- likely due to retention of urine in kidneys (urinary stasis) within dilated collection ducts - with outflow of collection ducts compromised by uterine suppression, esp for right kidney (slower urine flow)

Question 27

[renal adaptations] why can glucosuria and proteinuria occur

Answer 27

- due to increased GFR and reduced reabsorption in renal tubules

Question 28

should glucosuria be investigated even though mild glucosuria can be physiological in pregnancy

Answer 28

- yes as may indicate gestational diabetes mellitus

Question 29

[renal adaptations] what do increased frequency and urgency of urination reflect physiological from pregnancy

Answer 29

- increased urine production - bladder compression esp later in pregnancy

Question 30

[respiratory adaptations] maternal respiratory system has to adapt during pregnancy to achieve:

Answer 30

- meet increased requirements for oxygen - clear carbon dioxide from both maternal and foetal systems

Question 31

[respiratory adaptations] adaptations occur despite upward compression of lungs due to what

Answer 31

expanding uterus

Question 32

[respiratory adaptations] list important respiratory FUNCTIONAL changes during pregnancy

Answer 32

- O2 consumption increase by 30% - 20-50% increase in minute ventilation (volume of air passing thru lungs per minute) - 30-50% increase tidal volume (500ml -> 700mL) - small incr RR 1-2 breaths per minute - increased ventilation (exchange of air between lungs and outside air) - 10-25% decrease in functional residual capacity (volume of air remaining in lungs upon normal passive exhalation)

Question 33

[respiratory adaptations] what does the 20-50% increase in minute ventilation (volume of air passing thru lungs per minute) help

Answer 33

- help to meet increased demand for O2

Question 34

[respiratory adaptations] how does the 20-50% increase in minute ventilation (volume of air passing thru lungs per minute) help meet increased O2 demand

Answer 34

- mostly due to increasing tidal volume (amount of air move thru lungs each time inhale and exhale)

Question 35

[respiratory adaptations] how does ventilation (exchange of air between lungs and outside air) increase

Answer 35

- partly due to effects of progesterone - that increases sensitivity of brain respiratory centres to CO2 => ventilation increases more steeply in response to increasing circulating CO2 than in non-pregnant person

Question 36

[respiratory adaptations] why do pregnant women have lower O2 reserves and more susceptible to become hypoxic - 2 reasons

Answer 36

- higher oxygen consumption - lower functional residual capacity

Question 37

[respiratory adaptations] what do the respiratory functional changes in pregnancy lead to in PaO2 and PaCO2

Answer 37

- higher PaO2 (oxygen pressure in arterial blood) - PaCO2 lower

Question 38

[respiratory adaptations] what does higher PaO2 and lower PaCO2 facilitate with the foetus

Answer 38

- facilitates O2 and CO2 exchange with the foetus - occurring down concentration gradients

Question 39

[respiratory adaptations] what does resulting higher PaO2 and lower PaCO2 result in & what does this do

Answer 39

- result in mild respiratory alkalosis (PH> 7.4) - which may benefit O2 exchange across placenta - despite partial compensation by increased renal excretion of bicarbonate (to make more acidic)

Question 40

[respiratory adaptations] what are the key respiratory STRUCTURAL changes during pregnancy

Answer 40

- elevation of diaphragm by 4-6cm due to expanding uterus - maintenance of lung volume by expansion of rib cage

Question 41

[respiratory adaptations] in respiratory structural change where rib cage expands to maintain lung volume, how does this occur?

Answer 41

- ligaments connecting ribs to sternum relax <- response to elevated progesterone and relaxin (from pregnancy) - intercostal angle increases ~50% as rips move upwards and outwards - rib cage perimeter increases due to increases in transverse diameter

Question 42

[respiratory adaptations] after respiratory structural change, should spirometry parameters remain normal?

Answer 42

- yes (since expansion of ribcage largely maintains lung volume)

Question 43

if there is abnormal spirometry parameters in a pregnancy and how should it be investigated considering pregnancy indication

Answer 43

- yes - should be investigated as indicating potential respiratory disease, not considered as due to pregnancy

Question 44

[respiratory adaptations] there are changes to shape and location of ribcages during pregnancy, what happens to ribcage volume

Answer 44

- stays stable

Question 45

[respiratory adaptations] what are the clinical consequences of respiratory adaptations during pregnancy

Answer 45

- 60-70% normal pregnant women felt dyspnoea (shortness of breath) by thirs trimester

Question 46

[respiratory adaptations] is dyspnoea a physiological change & what is a physiological change with pregnancy

Answer 46

- yes - physiological change is a change in normal for an organism to maintain homeostasis under different circumstances

Question 47

[respiratory adaptations] does the dyspnoea reported occur with hypoxia

Answer 47

no

Question 48

[feeding and digestive system adaptations during pregnancy] women carrying a singeton foetus gain how much % of their pre-pregnancy weight

Answer 48

10-15%

Question 49

[feeding and digestive system adaptations during pregnancy] what weight is included in the weight-gain during pregnancy

Answer 49

- foetal weight gain - placental weight gain - deposition of adipose depots (fat) to support subsequent lactation

Question 50

[feeding and digestive system adaptations during pregnancy] pregnancy requires increased energy and nutrient needs, what adaptations are made

Answer 50

- enable increased food take - enable increased food absorption

Question 51

[feeding and digestive system adaptations during pregnancy] how much does food intake increase by in third trimester & briefly how is this possible

Answer 51

~10% - made by adaptations to central (brain) and peripheral (in GI tract) mechanisms which regulate food intake

Question 52

[feeding and digestive system adaptations during pregnancy] what are the maternal adaptations in CNS that enable increased food intake during pregnancy w/ MoA

Answer 52

- resistance to action of leptin in brain -> increases in circulating leptin during pregnancy do not inhibit appetite

Question 53

[feeding and digestive system adaptations during pregnancy] what are the maternal adaptations in PNS that enable increased food intake during pregnancy w/ MoA

Answer 53

- decreased gastric sensing of stretch -> enable larger meals to be eaten before fullness signals satiety

Question 54

what is leptin

Answer 54

- hormone produced by adipose tissue (body fat) cells - helps body maintain your normal weight on long-term basis by regulating hunger - provides sensation of satiety (feeling full)

Question 55

[feeding and digestive system adaptations during pregnancy] maternal adaptations that enable increased food absorption

Answer 55

- increased size and weight of small intestine - slowed motility of small intestine during pregnancy due to rising progesterone

Question 56

where in the body is the main site of nutrient absorption

Answer 56

small intestine

Question 57

[feeding and digestive system adaptations during pregnancy] what change in macronutrient absorption seen in pregnancy regarding glucose & what does this suggest

Answer 57

- circulating glucose rises more after oral glucose, with a delayed peak, in pregnant women - suggests increase in small intestine capacity to absorb glucose

Question 58

[feeding and digestive system adaptations during pregnancy] change in which micronutrient absorption is seen in pregnancy & what are they critical for

Answer 58

- absorption of iron, calcium, zinc - incr during pregnancy - these micronutrients are critical for foetal development and later, milk production

Question 59

[feeding and digestive system adaptations during pregnancy] what clinical consequences of gastrointestinal adaptations during pregnancy are there: (% affected included)

Answer 59

- dyspepsia - affects 17-45% pregnant women - constipation - more common during pregnancy than in general population; affects 11-38% of pregnant women

Question 60

what is dyspepsia

Answer 60

pain / discomfort in the stomach such as indigestion and heartburn

Question 61

[feeding and digestive system adaptations during pregnancy] why is constipation a common clinical consequence of the GI adaptations made during pregnancy

Answer 61

- constipation - due to reduced motility (adaptation) of GI tract - and due to compression of GI tract from enlarged uterus

Question 62

[feeding and digestive system adaptations during pregnancy] in maternal adaptation to enable increased food absorption, there is reduced motility of small intestine due to progesterone, MoA?

Answer 62

- progesterone action on smooth muscle in gut to relax => don't push food through GI system as quickly => increases time that gut contents (food) are in small intestine => more contact between food & surfaces of small intestinal - where absorption occurs -> promote nutrient absorption