7- Normal pregnancy and labour (Physiological changes in pregnancy)

Question 1

In order to meet with the demands of pregnancy, physiological adaptations occur in the mother. These adaptations allow her to support and protect the foetus. Which systems are affected?

Answer 1

• Endocrine
• Cardiovascular
• Respiratory
• Gi
• Urinary
• haematological

Question 2

endocrine system: sex hormones

Answer 2

Oestrogen and progesterone increase during pregnancy
- Oestrogen – produced by the placenta
- Progesterone being produced by the CL and later by the placenta

Question 3

endocrine system: Progesterone

Answer 3

• Maintains pregnancy
• Prevents contraction
• Suppresses the mother immune reaction fetal antigens

Question 4

endocrine system: Progesterone

Answer 4

• Maintains pregnancy
• Prevents contraction
• Suppresses the mother immune reaction fetal antigens

Question 5

endocrine system: Progesterone

Answer 5

• Maintains pregnancy
• Prevents contraction
• Suppresses the mother immune reaction fetal antigens

Question 6

endocrine system: Progesterone

Answer 6

• Maintains pregnancy
• Prevents contraction
• Suppresses the mother immune reaction fetal antigens

Question 6

endocrine system: Progesterone

Answer 6

• Maintains pregnancy
• Prevents contraction
• Suppresses the mother immune reaction fetal antigens

Question 6

endocrine system: Progesterone

Answer 6

• Maintains pregnancy
• Prevents contraction
• Suppresses the mother immune reaction fetal antigens

Question 7

endocrine system: thyroid hormones

Answer 7

• Increased levels of oestrogen results in increase in hepatic production of thyroid binding globulin (TBG)
• therefore more T3 and T4 bind to the TBG
• therefore more TSH is released by the AP gland
• therefore freee T3 and T4 levels remain unchanged, but total T3 and T4 levels increase

Question 8

Why do levels of thyroxin need to increase?

Answer 8

• Thyroxin is essential for foetus’ neural development, however the thyroid gland doesn’t function until second trimester
• Therefore increasing T3/T4 levels in mother ensures a constant supply of thyroxin in early pregnancy

Question 9

endocrine system: anti-insulin hormones

Answer 9

During pregnancy (mainly 2nd tri) there is an increase in:

• Placental lactogen
• Prolactin- suppresses FSH and LH
• Cortisol – due to rise in ACTH

Question 10

endocrine system: anti-insulin hormones affect on glycaemic control

Answer 10

• Therefore insulin resistance increases and therefor peripheral uptake of glucose decreases
• Glucose levels in blood increases ensuring continuous supply of glucose for foetus

Question 11

endocrine system: why is ketoacidosis a risk due to insulin resistance cause by anti-insulin hormones?

Answer 11

• The mother switches to an alternative source of energy which is provided by lipids.
• The increase in lipolysis means that there is an increase in free fatty acids in the plasma which provide substrate for maternal metabolism.
• The breakdown of lipids can result in ketogenesis

Question 12

Gestational diabetes mellitus

Answer 12

• normally as insulin resistance which occurs in pregnancy is counteracted by increasing insulin production
• In women with gestational diabetes, this compensatory oncrease does not occur- therefore hyperglycaemia
• RF: age, high BMI, family history of T2DM, smoking

Question 13

endocrine system: PTH and calcium

Answer 13

• Calcium for the growth of the babies bones used up
• Stimulation of Parathyroid
• Causes increase in PTH :
  o Increase 25(OH) D
  o Increase alpha hydroxylase which activates 25(OH) D to vitamin D -> increases Ca and phosphorus absorption
• Mother needs to eat food rich in calcium

Question 14

endocrine system: other hormones affected

Answer 14

• Increased melanocyte stimulating g hormone – increased pigmentation (linea nigra and melasma)
• HCG rise , doubling every 48hours and plateauing around 8-12 weeks, then falling

Question 15

resp system: anatomical changes

Answer 15

• Expanding uterus causes upwards displacement of diaphragm
• However total lung capacity doesn’t change that much because there is also an increase in the transverse and anterior posterior diameters of the thorax

Question 16

respiratory system: why does minute ventilation rate and tidal volume increase

Answer 16

• increased metabolic rate during pregnancy- increases demand for oxygen
• Minute ventilation rate and tidal volume increases to help mother meet oxygen demand

Question 17

respiratory system: resp alkalosis

Answer 17

• Hyperventilation experienced in pregnancy due to increased CO2 production and increased respiratory drive caused by progesterone
• Hyperventilation causes respiratory alkalosis – compensated by increased renal bicarbonate excretion

Question 18

GI sytem: reflux

Answer 18

GI reflux causing heart burn, N and V
- Expanding uterus can cause upwards displacement of the stomach
- Increases intra-gastric pressure
- progesterone also causes relaxation of oesophageal sphincter

Question 19

GI system: appendix

Answer 19

• Moves to the right upper quadrant as the uterus enlarges

Question 20

GI system: Gut motility

Answer 20

• Progesterone causes smooth muscle relaxation, decreasing gut motility
• Benefit- more time for nutrient absorption
• Negatives- constipation

Question 21

GI system: structural changes

Answer 21

• Gravid uterus can displace bowel causing mechanical obstruction

Question 22

GI system: relaxation of gallbladder

Answer 22

• due to progesterone
• Biliary tract stasis- gallstones predisposition

Question 23

GI system: ALP

Answer 23

ALP levels increase due to placental synthesis

Question 24

haematological system: VTE

Answer 24

Increased risk of thromboembolic disease
- Increase in fibrinogen and clotting factors in the blood
- Decrease in fibrinolysis
- Progesterone causes stasis of blood occurs
- LMWHeparin only option for anticoagulation in pregnancy

Question 25

haematological changes: dilutional anaemia

Answer 25

• During pregnancy, the plasma volume increases significantly, however, the red cell mass does not increase by as much

Question 26

haematological changes: others

Answer 26

• Increased white blood cells
• Decreased platelet count
• Increased ESR and D-dimer
• Increased alkaline phosphatase (ALP), up to 4 times normal, due to secretion by the placenta
• Reduced albumin due to loss of proteins in the kidneys
• Calcium requirements increase, but so does gut absorption of calcium, meaning calcium levels remain stable

Question 27

urinary system: eGFR and urea and creatinine

Answer 27

• Increased cardiac output during pregnancy causes an increase in renal plasma flow, which increases the GFR by about 50-60%. This would mean that there is an increase in renal excretion, so in pregnancy, the levels of urea and creatinine will be lower.
• Increased urine output – increased urinary frequency
• Loss of protein in the urine

Question 28

urinary system: RAAS

Answer 28

Increased RAAS
- Increases salt and water reabsorption and retention-> increase blood volume

Question 29

urinary system: anatomy

Answer 29

• Progesterone causes relaxation of the uterus (resulting in hydroureter) and relaxation of the muscles of the bladder
• Together these changes causes urinary stasis -> UTI -> pyelonephritis
• Physiological hydronephrosis due to the dilatation of ureters and collecting system

Question 30

MSK: back pain

Answer 30

Change in centre of gravity
- Increased lordosis and kyphosis
- Forward flexion of neck

Stretching of abdominal muscles
- Impede posture
- Strain paraspinal muscles

Question 31

MSK: Pelvic pain

Answer 31

o Increased mobility of sacroiliac joints and pubic symphysis
o Anterior tilt of pelvis

Question 32

MSK: Pelvic pain

Answer 32

o Increased mobility of sacroiliac joints and pubic symphysis
o Anterior tilt of pelvis

Question 33

MSK: Carpal tunnel

Answer 33

• Fluid retention can cause compression structures such as median nerve (carpal tunnel)

Question 34

Skin adapations

Answer 34

Question 35

immune system: why is the immune system weakened

Answer 35

Parasite- genetically different

Fetus= hemi-allograft
- Recognised by maternal immune system

Question 36

immune system: what causes immunosuppression

Answer 36

• Increase in ACTH- increases steroid hormone cortisol which causes immunosuppression
• Higher attack rate and severity of certain viral pathogens i.e. varicella, flu etc
  - May improve certain autoimmune conditions

Question 37

Cardiovascular system: changes

Answer 37

• Increased blood volume
• Increased plasma volume
• Increased cardiac output, with increased stroke volume and heart rate
• Decreased peripheral vascular resistance (due to progesterone)
• Decreased blood pressure in early and middle pregnancy, returning to normal by term

Question 38

Cardiovascular system: changes

Answer 38

• Increased blood volume
• Increased plasma volume
• Increased cardiac output, with increased stroke volume and heart rate
• Decreased peripheral vascular resistance (due to progesterone)
• Decreased blood pressure in early and middle pregnancy, returning to normal by term

Question 39

cardiovascular system: varicose veins

Answer 39

Varicose veins can occur due to peripheral vasodilation and obstruction of the inferior vena cava by the uterus

Question 40

cardiovascular system: what symptoms can peripheral vasodilation cause

Answer 40

flushing and hot sweats