7- Normal pregnancy and labour (Physiological changes in pregnancy) Flashcards
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?
- Endocrine
- Cardiovascular
- Respiratory
- Gi
- Urinary
- haematological
endocrine system: sex hormones
Oestrogen and progesterone increase during pregnancy
- Oestrogen – produced by the placenta
- Progesterone being produced by the CL and later by the placenta
endocrine system: Progesterone
- Maintains pregnancy
- Prevents contraction
- Suppresses the mother immune reaction fetal antigens
endocrine system: Progesterone
- Maintains pregnancy
- Prevents contraction
- Suppresses the mother immune reaction fetal antigens
endocrine system: Progesterone
- Maintains pregnancy
- Prevents contraction
- Suppresses the mother immune reaction fetal antigens
endocrine system: Progesterone
- Maintains pregnancy
- Prevents contraction
- Suppresses the mother immune reaction fetal antigens
endocrine system: Progesterone
- Maintains pregnancy
- Prevents contraction
- Suppresses the mother immune reaction fetal antigens
endocrine system: Progesterone
- Maintains pregnancy
- Prevents contraction
- Suppresses the mother immune reaction fetal antigens
endocrine system: thyroid hormones
- 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
Why do levels of thyroxin need to increase?
- 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
endocrine system: anti-insulin hormones
During pregnancy (mainly 2nd tri) there is an increase in:
- Placental lactogen
- Prolactin- suppresses FSH and LH
- Cortisol – due to rise in ACTH
endocrine system: anti-insulin hormones affect on glycaemic control
- Therefore insulin resistance increases and therefor peripheral uptake of glucose decreases
- Glucose levels in blood increases ensuring continuous supply of glucose for foetus
endocrine system: why is ketoacidosis a risk due to insulin resistance cause by anti-insulin hormones?
- 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
Gestational diabetes mellitus
- 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
endocrine system: PTH and calcium
- 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
endocrine system: other hormones affected
- Increased melanocyte stimulating g hormone – increased pigmentation (linea nigra and melasma)
- HCG rise , doubling every 48hours and plateauing around 8-12 weeks, then falling
resp system: anatomical changes
- 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
respiratory system: why does minute ventilation rate and tidal volume increase
- increased metabolic rate during pregnancy- increases demand for oxygen
- Minute ventilation rate and tidal volume increases to help mother meet oxygen demand
respiratory system: resp alkalosis
- 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
GI sytem: reflux
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
GI system: appendix
- Moves to the right upper quadrant as the uterus enlarges
GI system: Gut motility
- Progesterone causes smooth muscle relaxation, decreasing gut motility
- Benefit- more time for nutrient absorption
- Negatives- constipation
GI system: structural changes
- Gravid uterus can displace bowel causing mechanical obstruction
GI system: relaxation of gallbladder
- due to progesterone
- Biliary tract stasis- gallstones predisposition
GI system: ALP
ALP levels increase due to placental synthesis
haematological system: VTE
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
haematological changes: dilutional anaemia
- During pregnancy, the plasma volume increases significantly, however, the red cell mass does not increase by as much
haematological changes: others
- 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
urinary system: eGFR and urea and creatinine
- 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
urinary system: RAAS
Increased RAAS
- Increases salt and water reabsorption and retention-> increase blood volume
urinary system: anatomy
- 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
MSK: back pain
Change in centre of gravity
- Increased lordosis and kyphosis
- Forward flexion of neck
Stretching of abdominal muscles
- Impede posture
- Strain paraspinal muscles
MSK: Pelvic pain
o Increased mobility of sacroiliac joints and pubic symphysis
o Anterior tilt of pelvis
MSK: Pelvic pain
o Increased mobility of sacroiliac joints and pubic symphysis
o Anterior tilt of pelvis
MSK: Carpal tunnel
- Fluid retention can cause compression structures such as median nerve (carpal tunnel)
Skin adapations
immune system: why is the immune system weakened
Parasite- genetically different
Fetus= hemi-allograft
- Recognised by maternal immune system
immune system: what causes immunosuppression
- 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
Cardiovascular system: changes
- 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
Cardiovascular system: changes
- 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
cardiovascular system: varicose veins
Varicose veins can occur due to peripheral vasodilation and obstruction of the inferior vena cava by the uterus
cardiovascular system: what symptoms can peripheral vasodilation cause
flushing and hot sweats
