Physiology in Pregnancy Flashcards
What general changes occur during pregnancy?
- Mechanical (spine curves more)
- Metabolism (ketones produced after 12hrs without food)
- Fatigue – particularly early pregnancy
- Heartburn/reflux
- Oedema
- Thyroid
- General state of immunosuppression
- Weight gain- usually ~14kg over 40 weeks
What changes in the breasts occur during pregnancy?
Changes occur in glandular tissue not fat and are:
- Increased size
- Increased vascularity (causes breasts to be warm, tense and tender)
- Increased pigmentation of areola
- Secondary areola appears
- Montgomery tubercles appear on areola
- Colostrum-like fluid can be produced from end of first month (colostrum is the first milk produced by the mother and is rich in protein, antibodies and calories)
What cardiovascular changes occur during pregnancy?
- Increased circulating blood volume -50-70% of when non-pregnant
- Systemic vascular resistance falls – maximal at 20-32 weeks
- Increased blood flow
- Increased cardiac output (40%)
- Stroke volume increases (SVxHR= CO)
- Increased heart rate
- In supine position – 25% reduction in cardiac output (uterus compresses IVC, cannot resuscitate pregnant woman in supine position- left lateral tilt instead)
- Increased O2 consumption
When do most of the cardiovascular changes in pregnancy occur?
In the first trimester
What cardiovascular changes occur during labour?
- Autotransfusion of contractions (contractions squeeze blood out of uterus and cause up to ½ a litre increase in circulating volume)
- Increasing catecholamines (caused by pain)
- Cardiac output increased by 10% during labour and by 80% in the hour post-delivery
What cardiovascular changes occur post-partum?
- Return to normal by 3 months
- Blood volume decreases by 10% 3 days post delivery then slowly returns to normal
- BP initially falls then increases again days 3-7(pre preg levels by 6 weeks)
- SVR increase over first 2 weeks to 30% above delivery levels
- HR returns to pre preg over 2 weeks
What respiratory changes occur during pregnancy?
- 20% increase in oxygen demand
- 40-50% increase in minute ventilation
- Increased respiratory rate
- Increased tidal volume
- Decreased functional residual capacity (due to full uterus compressing lungs)
- Decreased PCO2 ↓
How can physiological dyspnoea in pregnancy be differentiated from pathological dyspnoea?
Physiological dyspnoea will be worse at rest and resolve when moving, the opposite of pathological.
What renal changes occur during pregnancy?
- Dilatation of the urinary collecting system – more pronounced on right
- Increased renal plasma flow – 60-80% by end of second trimester
- GFR and creatinine clearance increases by up to 50%
- Protein excretion increased
- Microscopic haematuria may be present
- Glycosuria common
- Urate increases with increasing gestation
- Urea and creatinine decreases
What are the upper limits for normal urea and creatinine during pregnancy?
Urea- 4mmol/L
Creatinine- 50-60µmol/L
What haematological changes occur during pregnancy?
- Plasma volume increases with birthweight
- Decreased haemoglobin, haematocrit and red cell count
- Dcreased platelet count
- 2-3 fold increase in requirement for iron
- 10 -20 fold increase in folate requirements
- WCC increases
- Hypercoaguable
How do the lab values for haemoglobin change in pregnancy?
Decrease
How do the lab values for white cell count change in pregnancy?
Increase
How do the lab values for platelet count change in pregnancy?
Decrease or stay same
How do the lab values for CRP change in pregnancy?
Stays same
