Physiology in Pregnancy Flashcards
What are the general changes in the body associated with pregnancy?
Mechanical
Metabolism
Fatigue – particularly early pregnancy
Heartburn/reflux
Oedema
Breasts
Thyroid
General state of immunosuppression
Weight gain
What happens to metabolism?
Anabolic then quickly becomes catabolic to allow nutrient supply to the foetus
Do you get insulin resisitance?
Yes-almost 2x increase in insulin
What can occur due to the increase in triglyceride breakdown?
Can get starvation Ketoacidosis-within 24-48 hrs can become very acidotic when pregnant & this happens
DKA is very dangerous in preg and can result in what?
IUD
What rate doubles in preg?
BMR
What is gestational diabetes?
Insulin resistance & hyperglycaemia of pregnancy
More likely to develop T2DM (should be checked once a year-mitigate risk with lifestyle factors)
What are the 3 things associated with Preeclampsia?
- High BP
- Oedema
- Proteinuria
What percentage get oedema & is this always physiological?
70-80% get oedema- physiological mostly but can be indicative of pathology such as pre-eclampsia
When do significant changes occur to the CV system?
Early in the first trimester
By how much does circulating BV increase?
50-70% of non pregnant
Does systemic vascular resistance increase or decrease?
DECREASE-maximal at 20-32 weeks
Do each of these increase or decrease?
1. Blood flow
2. CO
3. SV
4. HR
5. 02 consumption
- Increases
- Increases
3, Increases (SVxHR=CO) - Increases
- Increases
ALL INCREASE
What happens to CO in supine position?
25% reduction in CO
What do prostacyclin’s do?
Decrease systemic vascular resistance
In what trimester does BP tend to drop?
BP tends to drop in middle trimester & then rise-those who don’t drop are more inclined to be the ones to have pre-eclampsia
What are the intrapartum CV changes that occur?
-Autotransfusion of contractions
-Pain-increasing catecholamines
-CO increases by 10% in labour & by 80% in 1st post delivery hour (then continues to fall over the next 24 weeks)
When in the post partum period do CV changes return to normal?
3 months (mostly)
BV decreases by how much 3 days post delivery?
10%
How does BP adjust in the postpartum period
BP initially falls then increases again days 3-7(pre preg levels by 6 wks)
What happens to SVR & HR in the postpartum period?
-SVR increase over first 2 wks to 30% above delivery levels
-HR returns to pre preg over 2 weeks
Minute ventilation increases by what?
40-50%
Do these increase or decrease?
1) O2 demand
2) RR
3) TV
4) FRC
5) PCO2
1) INCREASE
2) INCREASE
3) INCREASE
4) DECREASE
5) DECREASE
What happens to PEFR & FEV1?
UNCHANGED
What is the foetuses respiratory system?
Placenta
What happens to thoracic circumference when the diaphragm moves up?
Thoracic circumference increases (May get splaying of ribs)
What happens to the acid base balance?
C02 will be increased & PO2 tends to sit higher
What happens to the O2Hb dissociation curve?
Shifts to the right-decreased affinity for oxygen
What happens to the urinary collecting system & where is this more pronounced?
Dramatic dilation-more pronounced on right (more effected by hydronephrosis)
Physiological Hydronephrosis
Due to relaxation of the smooth muscle of the ureter caused by progesterone as well as the mechanical compression by the growing uterus
..?.. renal plasma flow – 60-80% by end of second trimester settling to 50% increase through the third trimester
INCREASED
GFR ..?.. & creatinine clearance ..?.. by up to 50%
INCREASES (both)
Means normal levels of urea & creatinine are much lower during pregnancy
..?..uria is common
Glycosuria
Microscopic ..?.. may be present
Haematuria (can be the result of the progesterone)
Does protein excretion increase?
YESSS
What increases with increasing gestation?
URATE
UREA ..?.., Creatinine ..?..
BOTH DECREASE
Urethra shortens: what does this mean for UTI risk and ability to empty bladder?
More risk of UTI & also harder to empty bladder as easily
UTIs should be treated promptly with Abx which are known to be safe in pregnancy
What increases compared to birthweight?
PV
Hb, Haematocrit and RCC all do what in pregnancy?
DECREASE
Is there any change to MCV or MCHC?
NO Change
Platelet count increases: True or false?
FALSE
Platelet count decreases
2-3 fold increase in the requirement for what?
IRON
10-20 fold increase in what requirements?
FOLATE Requirements
What supplement reduces the risk of conditions like spina bifida?
FOLIC ACID
WCC Increase: True or false?
TRUE (& neutrophil count is increased - a WCC of up to 16x109/L is normal in pregnancy)
In terms of Haematological changes what kind of state is pregnancy?
Hypercoagulable state
These changes in the coagulation system occur from very early in pregnancy and can persist for up to 6 weeks after delivery. Half of all blood clots associated with the antenatal period occur in the first 15 weeks of pregnancy.
Why are pregnant people more prone to back pain during (and after) pregnancy?
Wth weight gain, an increased BV & enlarging fetus, the centre of gravity no longer falls over the feet. So as to not be constantly falling over, the pregnant person needs to lean backward and the curves of the spine change along its whole length
What hormones cause increased pliability & extensibility of connective tissue?
Relaxin (hormone produced during pregnancy) & increased levels of oestrogen & progesterone
Ligamentous joints become less stable during pregnancy: What joints are particularly affected to allow for the birth of the baby?
Symphysis pubis & sacroiliac joints
The normal pubic symphyseal gap of 4-5mm increase on average by what?
Another 3mm
When does joint loosening occur & when should it return to normal?
Starts as early as 10 weeks but should return to “normal” 4-12 weeks post partum
By term there is an increased load on the ..?.. joints of 2.8 times the normal value when standing.
HIP
BMR increases in pregnancy. During pregnancy metabolism changes to ensure what?
Adequate nutrition for foetal growth
Why is pregnancy a time of relative insulin insensitivity?
Human placental lactogen produced by the placenta acts against maternal insulin
Why is there an increased storage of lipids in maternal tissues?
FAs are vital for foetal organogenesis
What weight gain throughout pregnancy would be considered normal?
10-14kg
What is the likely reason for fatigue & when is it at its worse?
Can be overwhelming during the first trimester
Likely due to hormonal changes
Tends to get better in the second trimester.
It often returns towards the end of pregnancy when it is more likely due to the increased work load of advanced pregnancy, discomfort and difficulty sleeping.
What are the causes of Heartburn/reflux in pregnancy?
During pregnancy food moves more slowly into the stomach & there is delayed emptying.
Hormones also cause relaxation of the lower oesophageal sphincter so contents are more likely to reflux from the stomach back into the oesophagus.
The mechanical pressure from an enlarging uterus makes this worse as does delayed gastric emptying.
Why is heartburn/reflux in pregnancy one of the reasons why GA is much higher risk in pregnancy?
Changes mean the risk of aspiration is much higher and increases with advancing pregnancy.
The introduction of regional anaesthesia (spinals and epidurals) made a huge difference to morbidity and mortality of operative procedures in maternity patients.
Why do 80% of pregnant people develop some oedema particularly towards term?
Physiological sodium & water retention & decreased ability to excrete sodium & water load
Increased BV & decreased VR due to compression of IVC from the gravid uterus also contributes to peripheral oedema