Physiology in Pregnancy Flashcards
What are the general physiological changes in pregnancy?
Mechanical Metabolism Fatigue Heartburn/reflux Oedema Breast changes Thyroid changes General state of immunosuppression Weight gain
Why do mechanical changes occur?
Skeletal changes occur to accommodate the change in centre of gravity, there is a change in spinal curvature and relaxin causes the relaxation of all joints
What is the average weight gain in pregnancy?
14kg
Why does heartburn/reflux occur in pregnancy?
Sphincter at the top of the stomach relaxes due to relaxin
Stomach is generally more acidic
Increased pressure from growing uterus/foetus
What percentage of women get oedema in pregnancy? Why?
80% will have it by 3rd trimester due to osmotic changes, plasma changes, slowed venous return
What are the thyroid changes in pregnancy?
Can enlarge due to relative iodine deficiency
What are the breast changes in pregnancy?
Increased size and vascularity
Increased pigmentation of areola and nipple
Secondary areola appears
Montgomery tubercles appear on the areola
Colustrum-like fluid can be expressed from the end of the 3rd month of pregnancy
Can feel lumpy
What does the increased size and vascularity of the breasts cause?
Causes them to become warm, tense and tender
What is the main indirect cause of maternal mortality?
Cardiac disease
What is the change in circulating blood volume in pregnancy?
Increased by 50-70% compared to non-pregnant women
What is the change in systemic vascular resistance? Why?
Systemic vascular resistance falls
Circulating prostaglandins cause relaxation of vessels, high volume of blood flowing through a relatively low pressure foetal/placental unit
What are the changes in blood flow, cardiac output and heart rate in pregnancy?
Blood flow increased
CO increased by 40%
HR increased 20-30bpm above normal
What is the change in cardiac output in the supine position in pregnancy?
25% reduction
Why should a pregnant woman be resuscitated in the left lateral position?
Relieve the pressure on the IVC from the uterus
What is the change in oxygen consumption in pregnancy? Why?
Increased
Demand from foetus, utero-placental unit, enlarged breasts and uterus
Why might there be intrapartum cardiac pain?
Increasing catecholamines increase BP and HR
What is the increase of cardiac output in labour and in the first hour post-delivery?
10% increase in labour
80% increase post-delivery
What mode of delivery carries better outcomes for most women with cardiac disease?
Epidural and vaginal delivery
When does the cardiovascular system usually return to normal after pregnancy?
By 3 months post-delivery
What is the change in blood volume 3 days post-delivery?
10%
What is the change in BP in the postpartum period?
BP initially falls, then increases again by days 3-7
Pre-pregnancy levels are reached by 6 weeks
What is the change in systemic vascular resistance in the postpartum period?
Increases over the first 2 weeks to 30% above delivery levels
When does HR return to normal after pregnancy?
Over 2 weeks post-delivery
What is the change in CO post-delivery?
80% increase in first hour post-delivery, then continues to fall in the next 24 weeks
What is the increase in oxygen demand in pregnancy?
20%
What is the increase in minute ventilation in pregnancy?
40-50%
What is the effect of pregnancy on respiratory rate, tidal volume and functional residual capacity?
RR increased
TV increased
FRC decreased
What is the effect of pregnancy on PEFR and FEV1, and PCO2?
PEFR and FEV1 unchanged
PCO2 reduced
What changes occur in the urinary collecting system in pregnancy?
Dramatic dilatation, more pronounced on the right
What is the change in renal plasma flow in pregnancy?
Increased, by 60-80% by the end of the second trimester
What is the change in GFR and creatinine clearance in pregnancy?
GFR increases
Creatinine clearance increases by up to 50%
What should be done if microscopic haematuria is detected in a pregnant woman?
Microscopic haematuria may be present and is ok as long as it is not associated with proteinuria or infection, but should be followed up after birth to ensure that urine returns to normal
What is the change in protein excretion, urate, urea and creatinine in pregnancy?
Protein excretion increased
Increasing urate with increasing gestation
Decreased urea and decreased creatinine
What are the changes in plasma volume in pregnancy?
Plasma volume increases with birthweight and as red cell mass increases
What are the changes in haemoglobin, MCV and MCHC in pregnancy?
Hb decreased
No changer MCV or MCHC unless iron deficiency anaemia
What is the increase in requirements for iron in pregnancy?
2-3 fold increase
What is the increase in requirements for folate in pregnancy?
10-20 fold increase
What is the effect of pregnancy on coagulation?
Pregnancy is a hyper-coagulable state
Clotting factors 8, 9 and 10 increase
Fibrinogen increases
What can be given to women to decrease the risk of PE?
Low molecular weight heparin
What is the effect of pregnancy on white cell count and platelets?
WCC increased
Platelets decreased
Why do platelets appear to be decreased in pregnancy?
Due to increase in plasma volume - not an actual decrease in platelets, relative decrease
What is the effect of pregnancy on CRP and ESR?
CRP unchanged unless infection present
ESR increased
What is the effect of pregnancy on 24-hour protein and total protein?
24-hour protein increased
Total protein decreased
What is the effect of pregnancy on albumin, AST, ALT and GGT?
Albumin decreased
AST, ALT and GGT slightly decreased or no change
What is the effect of pregnancy on alkaline phosphatase?
Greatly increased because placenta produces alkaline phosphatase
What is the effect of pregnancy on bile acids?
No change - if raised can be used to diagnose cholestasis of pregnancy
What is the effect of pregnancy on D-dimer?
Increased
