Maternal Physiological Changes in Pregnancy

Question 1

Describe some of the effects that growth of the uterus has on the anatomy of the mother

Answer 1

• weight gain
• pressure on IVC impeding venous return from lower limbs
• hormonal effects: relaxation of vessels and valves (can cause varicose veins)

Question 2

Describe the effects that pregnancy has on the mothers MSK system

Answer 2

• centre of gravity changes resulting in accentuated lumbar lordosis (backache, anterior flexion of neck, waddling)
• relaxin softens ligaments (pelvic pain)
• striae gravidarum (stretch marks)
• diastasis recti (abdo splitting and increase in rectus abdominis)

Question 3

What makes hCG and what does it do?

Answer 3

• made by trophoblast cells of the embryo under direction from progesterone and oestrogen
• prevents regression of corpus luteum at the end of menstrual cycle

Question 4

What makes hPL and what does it do?

Answer 4

• made by syncytiotrophoblast cells of placenta
• promote development of mammary glands
• decrease insulin sensitivity and utilisation of glucose by mother
• involved in releasing fatty acids from mother’s fat stores

Question 5

What are the effects of oestrogen on pregnancy?

Answer 5

• enlarge mothers uterus, breasts and ductal structure
• enlarge external genitalia
• relax pelvic ligaments

Question 6

What are the effects of progesterone on pregnancy?

Answer 6

• develop the endometrium
• involved in nutrition of early embryo
• decrease contractility of uterus (prevents spontaneous abortion)
• helps oestrogen prepare breasts for lactation

Question 7

Describe the functional unit that the mother and foetus form in hormone production

Answer 7

• placenta is major source of progesterone and oestrogen
• but cannot manufacture adequate cholesterol
• and lacks 2 enzymes for making estrone and estradiol
• and lacks 1 for estriol
• so foetus contributes and supplies lacking enzymes and mother supplies most of cholesterol as LDL
• foetus couldn’t do it on its own as it lacks the catalyst enzymes for the last 2 steps

Question 8

Describe the cardiovascular changes during pregnancy

Answer 8

• CO increases in first trimester then only slowly during second and third trimesters
  (due to increase in SV and HR)
• MABP decreases during second trimester then increases during third trimester
  (though remains at or below normal)
  ( due to decrease in peripheral resistance from vasodilating effects of progesterone and estradiol, and expansion of placental circulation)
• blood volume increases in first trimester, expands in second and slowly increases then plateaus in third
  ( due to increase in plasma volume and number of erythrocytes)

Question 9

Describe the endothelial changes during pregnancy

Answer 9

• high oestrogen levels stimulate NO production

- relaxin from corpus luteum causes vasodilation by blocking endothelin induced vasoconstriction

Question 10

What are the normal physiological changes to pregnant women you would find on examination?

Answer 10

• peripheral oedema
• mild tachycardia
• JVP distension
• lateral displacement of left ventricular apex

Question 11

Describe pre-eclampsia and its treatment

Answer 11

• placental problem involving an increase in BP (>140/90mmHg), proteinuria, and oedema
• can involve failure of second wave of trophoblast invasion (which is supposed to impair capacity of spiral arteriles to constrict)
• delivery of baby

Question 12

What are the risk factors of pre-eclampsia?

Answer 12

• previous pregnancy with it
• over 40
• family history
• obesity
• primigravida (first pregnancy)

Question 13

What are the consequences of pre-eclampsia?

Answer 13

• poor placental perfusion can cause foetal growth restriction
• increased vascular resistance in placenta can cause:
• decreased blood flow
• hypertension in mother
• renal arteriolar endothelial damage (leading to oedema, glomerular damage and proteinuria)

Question 14

Describe the features of eclampsia and its interventions

Answer 14

• extreme hypertension (increased intracranial pressure, seizures with risk of haemorrhage)
• magnesium sulphate
• antihypertensives
• rapid delivery
• careful fluid balance

Question 15

Describe the changes to the respirator system during pregnancy

Answer 15

Increase in alveolar ventilation:

• level of diaphragm rises (due to relaxation from progesterone)
• decrease in RV and FRC
• little effect of resp rate but increase in tidal volume

Question 16

Describe the changes to the kidneys and urinary tract during pregnancy

Answer 16

• renal blood flow increases (due to CO)
• GFR increases
• urine output increases a bit due to increased fluid intake and load
• reabsorptive capacity of tubules to Na, Cl, and H20 increased (due to increased production of steroid hormones)
• decreased plasma urea, creatinine and uric acid
• bladder loses tone (progesterone) and is compressed by growing foetus

Question 17

Describe the changes to the GI tract during pregnancy

Answer 17

• uterus pressing against colon and rectum so constipation
• reduction in gut motility from progesterone
• heart burn from relaxation of lower oesophageal sphincter and GI smooth muscle