pregnancy physiology

Question 1

What general changes occur during pregnancy?

Answer 1

• mechanical
• metabolism
• fatigue
• heartburn/reflux
• oedema
• breasts
• thyroid
• immunosuppression

Question 2

what adaptation of systems occur in pregnancy

Answer 2

• cardiovascular
• respiratory
• haematological
• renal

Question 3

describe mechanical change during pregnancy

Answer 3

increased lumbar curvature to compensate for belly

ligamentous joints less stable because of relaxin, oestrogen and progesterone

Question 4

describe metabolic change during pregnancy

Answer 4

basal metabolic rate increases

gestational diabetes: human placental lactogen acts against maternal insulin

increased storage of lipids in maternal tissues

Question 5

why is heartburn/reflux more common in pregnancy

Answer 5

delayed emptying: food moves slowly into stomach

relaxation of lower oesophageal sphincters: hormones

mechanical pressure from uterus

Question 6

why is oedema more common in pregnancy

Answer 6

physiological sodium and water retention

increased blood volume

decreased venous return due to compression of IVC

Question 7

describe breast changes in pregnancy

Answer 7

• increased size and vascularity
• increased pigmentation of the areola and nipple
• secondary areola appears
• montgomery tubercles appear on areola

Question 8

when can colostrum be expressed?

Answer 8

From the end of the 3rd month

Question 9

describe thyroid changes during pregnancy

Answer 9

maternal iodine requirements are increased because iodine is actively transported into fetoplacental unit

hyperemesis gravidarum: hyperthyroidism due to increased levels of T4 but suppressed TSH

thyrotoxicosis: TSH receptor antibodies cross placenta and cause foetal hyperthyroidism
hypothyroidism: foetus is dependent on maternal thyroid function until foetal thyroid function begins at around 12 weeks gestation

Question 10

what are CVS changes in pregnancy?

Answer 10

• increased circulating blood volume (left ventricular end diastolic volume increased)
• systemic vascular resistance falls
• increased blood flow to organs
• increased cardiac output (increased stroke volume)
• increased heart rate
• increased O2 consumption

Question 11

why should a pregnant woman never lie supine

Answer 11

vena caval compression by uterus results in 25% loss of cardiac output and woman will faint

Question 12

what are respiratory changes in pregnancy?

Answer 12

increased O2 requirements

• tidal volume increases
• respiratory rate increases (SOB)
• CO2 levels decreases (relative hyperventilation)
• functional residual capacity decreases

Question 13

what are haematological changes in pregnancy

Answer 13

• circulating blood volume increases
• red cell mass increases
• plasma volume increases (platelet count decreases)
• iron requirements increase
• folate requirements increase
• wcc and neutrophil count increase
• hypercoaguable state (clotting factors increases, fibrinolytic activity decreases)

Question 14

what are renal system changes in pregnancy?

Answer 14

• dilatation of the urinary collecting system (relaxation of ureter smooth muscle by progesterone and mechanical compression by the growing uterus)
• increased renal plasma flow (increases circulating blood volume, decreased systemic vascular resistance)
• increased glomerular filtration rate and creatinine clearance
• glycosuria, microscopic haematuria, UTI|s