S6) Maternal Physiological Adaptations in Pregnancy Flashcards
Identify the 3 types of changes in maternal physiological adaptation to pregnancy
- Biochemical changes
- Physiological changes
- Structural changes
Why do maternal physiological adaptations to pregnancy occur?
- Provide a suitable environment for the nutrition, growth and development of the foetus
- Prepare the mother for birth
- Prepare the mother for support of the new born
Identify the 6 hormones which orchestrate maternal physiological adaptations to pregnancy
- hCG
- Progesterone
- Oestrogen
- Relaxin
- hPL
- Inhibin
hCG is released from the synctiotrophoblast.
What role does it have in early pregnancy?
hCG mimics the action of LH and maintains the corpus luteum so it can produce oestrogen and progesterone until the placenta can take over
hCG reduces the maternal levels of IgA, IgG and IgM.
Why is this beneficial to the foetal-placental unit?
The maternal antibodies do not attack the foetus as a foreign antigen
hCG reduces the maternal levels of IgA, IgG and IgM.
What consequence does this have on the mother?
The mother becomes slightly immunodeficient and is at increased risk of developing infections
Progesterone relaxes smooth muscle.
Identify 4 effects of increasing progesterone levels on the GI tract function which the mother may complain of?
- Vomiting
- Constipation
- Heartburn
- Indigestion
Which oestrogen level in the maternal serum/urine best indicates foetal progress and why?
Oestriol (E3) as it shows the development of the liver and has its own singular pathway
Identify 3 hormones which stimulate breast growth
- Oestrogen
- Progesterone
- Prolactin
How does inhibin (from the corpus luteum and placenta) prevent further pregnancies from occuring in the pregnant state?
Inhibin prevents follicular development by inhibiting FSH
Glucose and amino acid metabolism are altered in pregnancy to favour the nutritional supply to the foetus.
Identify 4 of these changes
- Reduction in maternal [blood glucose] and [amino acid]
- Diminished maternal response to insulin in second ½ of pregnancy
- Increased maternal free fatty acid, ketone and triglyceride levels
- Increased insulin release in response to a normal meal
Identify the 4 hormones which orchestrate the changes in glucose and amino acid metabolism in pregnancy
- Prolactin
- Oestrogen
- Progesterone
- hPL
What effect does progesterone have on glucose metabolism?
Progesterone stimulates appetite in the first half of pregnancy and diverts glucose into fat synthesis
What effect does oestrogen have on glucose metabolism?
Oestrogen stimulates an increase in prolactin release
Identify the 3 main hormones responsible for maternal resistance to insulin
- Prolactin
- hPL
- Cortisol
Describe the significance of maternal decline in glucose usage
- Gluconeogenesis increases, maximising the availability of glucose to the foetus
- Maternal energy demands are met by fatty acid metabolism (later in pregnancy)
What is the benefit of increased maternal deposition of fat by progesterone?
Prepares for higher energy demands from the foetus later in pregnancy
Which hormone is primarily responsible for changes in maternal carbohydrate metabolism during pregnancy?
Human placental lactogen (hPL)
As pregnancy progresses, the foetal-placental unit’s increasing nutritional needs aren’t met via maternal vascular-neogenesis.
Describe 2 changes which accomodate this
Changes in the function of maternal baroreceptors and volume receptors:
- Increased blood flow to the growing breasts, kidneys and Gi tract
- Plasma volume increases while peripheral vascular resistance falls
Identify 2 changes to the maternal heart which can be observed on examination
- Hypertrophy (eccentric)
- Upward displacement of flow murmurs
Plasma volume increases by 50% in pregnancy due to increased cardiac output. However, progesterone constantly increases too and relaxes smooth muscle.
What overall effect does this have on maternal BP?
BP = CO x TPR
- CO increases
- TPR decreases
- Notable increases/decreases in BP (fluctuations)
Identify 3 signs and symptoms of fluctuations in maternal BP
- Hot flushes
- Increased venous pooling
- Cankles (oedema in the feet)
Which 2 factors contribute to venous engorgement and distension seen in later pregnancy?
- Gravity increases venous pooling
- TPR decrease as less pressure pushes venous blood
Identify the 2 long-term sequelae that are attributed to a longer period of venous distension
- Varicose veins
- Haemorrhoids
Identify 3 major complications in pregnancy
- Gestational diabetes
- Anaemia
- Pre-eclampsia
What is Gestational diabetes?
- Gestational diabetes is high blood sugar that develops during pregnancy due to insufficient insulin production for pregnancy demands
- It commonly occurs in the second ½ of pregnancy and usually disappears after giving birth
If gestational diabetes is not controlled, how will the sustained hyperglycaemia affect foetal glucose levels?
Baby grows larger than normal resulting in:
- Difficulties pushing the baby through the birth canal
- Presdisposition of neonate to Type II diabetes
State 3 complications associated with poorly controlled maternal diabetes
- Jaundice
- Hypoglycaemia after birth
- Increased risk of birth defects to brain, heart & spinal cord
What is iron deficiency anaemia?
Iron deficiency anaemia is the reduction in the amount of healthy RBCs in blood due to a lack of iron
Identify 3 clinical features of blood which increase during pregnancy
- Plasma volume
- Blood volume
- Red cell mass
Which foetal demand does a high plasma flow meet?
Increased plasma flow provides high nutritional flow for foetus
Which foetal demand does a high blood volume and high red cell mass meet?
The following provides increased O2 supply:
- Increased red cell mass (stimulated by erythropoietin)
- Increased haemoglobin flow (blood volume)
Why does anaemia occur during pregnancy?
- More iron is used for haemoglobin to transfer O2 to foetus
- High iron turnover due to haemoglobin breakdown > production
State 3 signs and symptoms a mother would experience if she has anaemia
- Fatigue
- Pallor
- Dizziness
What treatments can be given to alleviate the symptoms of anaemia in pregnancy?
- Iron supplements
- Folate supplements (helps with iron absorption)
Predict 2 consequences of poor foetal-placental perfusion associated with anaemia in pregnancy
- Under-development issues: poor neurodevelopment & poor growth
- Anaemia/hypoxic baby
What effect does smoking during pregnancy have on the foetus?
- Tar accumulates and reduces ventilation ability
- Alveoli cannot diffuse enough O2 into blood
- Results in poor foetal-placental perfusion
What is pre-eclampsia?
Pre-eclampsia is a rapidly progessive disorder occuring only during pregnancy and the postpartum period characterized by hypertension and usually the proteinuria
What are the diagnostic criteria for pre-eclampsia?
- Systolic BP of 140/more
- Diastolic BP of 90/more
Other than proteinuria and hypertension, identify 5 other symptoms of pre-eclampsia
- Oedema
- Headache
- Nausea/vomiting
- Changes in vision
- Poor tendon reflexes
What signs or symptoms suggest that a mild pre-eclampsia is worsening in severity?
- Decreased kidney function: increased creatinine, urea, urate and creatine clearance
- Decreased liver function: increased AST and gamma-GT
Identify 2 examinations performed on a patient with suspected pre-eclampsia
- Examination of optic fundi
- Examination of tendon reflexes
Why would diseases of the respiratory system be more severe in pregnancy?
There is an increased oxygen requirement in gestation
Describe the changes in respiratory function which occur in pregnancy
- RR changes little
- Increased tidal volume and oxygen uptake
What is the effect of the increased tidal volume and oxygen uptake that is seen in pregnancy?
- Increased awareness of the desire to breathe (interpreted as dyspnoea)
- Lower pCO2
What role does progesterone have in the changes in respiratory function observed in pregnancy?
Progesterone acts on the chemoreceptors in the respiratory centre to induce increased respiratory effort and reduction in pCO2
What anatomical/mechanical effect does the expanding uterus have on the maternal respiratory system?
The expanding uterus pushes up on the xiphoid process and reduces room for lung expansion, hence reducing respiratory function
How does the renal function change during pregnancy?
- Increased renal blood flow raises GFR to 160% of normal
- Increased secretion of renin, aldosterone, angiotensin II compensate for expected sodium loss
- systemic vasodilation
- decreased PCT absorption
- smooth muscle relaxes (progesterone) so increases size of the kidney and ureters
- decreased speed of urine passage
What effect does the gravid uterus have on renal function?
- The gravid uterus rises from the pelvis and rest upon the ureters
- This compresses the ureters above the pelvic brim causing renal congestion
Pregnancy may be associated with increased urinary incontinence.
Why is this?
Gravid uterus places increased pressure on the bladder therefore the mother urinates more frequently
Why is there an increased risk of urinary tract infections in pregnancy?
- Progesterone dilates smooth muscle in the nephrons
- Results in pooling of urine in the distended parts of the urinary system
The placenta also contributes to the maternal synthesis of DHCC (calcitriol).
How does this active form of Vitamin D3 contribute to foetal growth?
Calcitriol in mother increases calcium reabsorption for the foetus to use for bone growth
what is the foetus seen as inside the mother
- it is seen as a parasite so immune regulation allows mum to be a good host
what are changes in respiration during pregnancy
- ventilation increase → mum can meet 02 demands and remove C02 at a fast rate
- Tidal volume →
- Pa(02) increases and Pa(Co2) decreases
- dysponea - shortness of breath due to hyperventilation
what changes are there in haematology/ CVS
- volume expansion: progesterone → smooth muscle relaxation so reduced SVR and drop in BP
- clotting mechanisms: more procoagulants, reduced anticoagulants and fibrinolysis
- Mum needs to fill utero-placental-fetal circulation, oxygenate the growing uterus and prepare for blood loss during delivery
- Dilutional anemia → Increase in space but not an increase in RBC
how does the body increase SV
- RAAS, drop in BP so increases BP
- oestrogen also stimulates RAAS
anemia in pregnancy
- red cell mass increases but not enough to counter the dilutional increase in PV
- most common cause is iron deficiency in pregnancy
- leads to:
- increase morbidity for mum and baby
- preterm delivery
- maternal fatigue
how does the GI tract change
- slower transit time
- increased absorption of nutrients and vitamins
- BUT: uterus can displace bowel and cause obstruction
- decreased bowel motility: more water absorption BUT constipation
- decreased gall bladder contractivity → gallstones
adaptations in the thyroid and parathyroid
- oestrogen stimulates Thyroid binding globulin
- increases thyroxine production
- parathyroid stimulates more calcium and phosphorus absorption
glucose metabolism in pregnancy
- fat is laid down in the first half of the pregnancy to help the fetus and its needs later on down the line
- reduction in maternal blood glucose and amino acids
- diminished insulin responsiveness in second half of pregnancy so more nutrients can reach the baby
- increase in maternal fatty acids and ketones for fuel
- increased insulin response to a meal
- HpL - is a hormone that causes resistance to insulin
what are some risk factors for gestational diabetes
- previous birth of a large baby
- previous gestational diabetes
- family history of diabetes
investigations and diagnosis if gestational diabetes
- oral glucose tolerance test
- diagnose if fasting plasma glucose is 5.6 mmol/L above or 2 hour plasma glucose is above 7.8
what is the mother at risk of if she has gestational diabetes
- preeclampsia
- premature labor
- shoulder dystocia → when the babies shoulder is stuck behind the pubic bone
- increase risk of developing type 2 DM
what are the risks of the baby if the mother has gestational diabetes
- macrosomia
- cardiac, renal, neural tube
- hypoxia and sudden death
- hypoglycaemia
- jaundice
what are some MSK adaptions
- centre of gravity changes:
- forward flex of neck
- more lordosis and kyphosis
- stretching of abdominal muscle:
- impede posture
- strain on paraspinal muscles
- increase of sacroiliac joints and pubic symphysis
= these can cause shoulder, back and pelvic pains and headaches
what is pre eclampsia
- new onset hypertension after 20 weeks
- proteinuria
- organ dysfunction
- uteroplacental dysfunction
- severe does not respond to treatment
what are some risk factors of pre eclampsia
- above 40 years
- pregnancy interval of more than 10 years
- family history
- multiple pregnancy
- pre existing renal disease
what is the pathogenesis of pre eclampsia
- impaired invasion of trophoblasts → Shallow invasions of spiral arteries
- hypoperfusion and ischemia and systemic endothelial dysfunction
