Session 8 - Preggers changes Flashcards
Give 6 main physiological changes in pregnacny
o Cardiovascular system o Urinary system o Respiratory system o Metabolic changes Carbohydrate Thyroid hormones o Gastrointestinal System o Immune system
What are the five main CVS changes of pregnancy
o Blood volume increases o Cardiac output increases o Stroke volume increase o Heart rate increases - Blood pressure DECREASES
What causes hypotension in T1 and T2?
Progesterone decreases systemic vascular resistance
What causes hypotension in T3
T3 – Aortocaval compression by gravid uterus. Reduced return to the heart.
Give four main effects of pregnancy on the urinary system
o Renal plasma flow increases
o Glomerular Filtration Rate (GFR) increases
~55%
o Filtration capacity intact
o Functional renal reserve decreases as GFR increases
Why does urinary stasis occur in pregnancy?
Progesterone relaxes the smooth muscle in the walls of the ureters, which can result in stasis, hydroureter, UTIs and pyelonephritis.
Why is pyelonephritis dangerous in pregnancy?
Pre-term labour
What is the main effect of foetus on respiratory system?
Diaphragm is displaced
What 7 changes occur in respiratory system?
O2 consumption increases 20% Decreases functional residual capacity Vital capacity unchanged Tidal volume increases Respiratory minute volume increased Alveolar ventilation rate increased Respiratory rate unchanged
What does progesterone generate in resp system?
Physiological hyperventilaton, so mother can blow off the extra CO2 the foetus produces.
This leads to respiratory Alkalosis, which the kidneys compensate for by producing and reabsorbing less bicarbonate.
How is carbohydrate metabolism changed in pregnancy?
Glucose and amino acid metabolism are altered in pregnancy to favour nutritional supply to the fetus
What does progesterone stimulate in terms of carbohydrate metabolism?
Progesterone stimulates appetite in the first half of pregnancy and diverts glucose into fat synthesis
What does oestrogen stimulate in terms of carb metabolism?
. Oestrogen stimulates an increase in prolactin release, which, along with other hormones, generates a maternal resistance to insulin
Why is it good to increase insulin resistance in mother?
More glucos for foetus
How are mothers energy needs met later in the pregnancy?
etabolising peripheral fatty acids.
What is gestational diabetes?
o Carbohydrate intolerance first recognised in pregnancy and do not persist after delivery
o Risks associated with poor control
Macrosomic fetus
Stillbirth
Increased risk of congenital defects
o Oral glucose tolerance test required
How do pancreatic b cells meet increased demand for insulin secretion
by b-cell hyperplasia and hypertrophy as well as the increased rate of insulin synthesis in the b-cell.
Why does gestational diabetes arise?
In some women, the endocrine pancreas is unable to respond to the metabolic demand of pregnancy and the pancreas fails to release the increased amounts of insulin required.
What happens to lipid metabolsim in pregnancy?
o Increase in lipolysis from T2
o Increase in plasma concentration of free fatty acids on fasting
Free fatty acids provide substrate for maternal metabolism, leaving glucose for the fetus
o Increased utilisation of free fatty acids increases the risk of Ketoacidosis
Combined with pregnancy’s state of compensated respiratory alkalosis this can be extremely bad.
What happens to thyroid in pregnancy?
o Thryoid binding globulin production increased
o T3 increased
o T4 increased
o Free T4 in normal range due to increased binding globulin
o hCG has a direct effect on the Thryoid, stimulating T3 and T4 production
TSH can be decreased in normal pregnancies as a result of negative feedback from T3 and T4 produced due to hCG secretion
What anatomical GI changes occur during preg?
o Alterations in the positions of viscera
E.g. appendix moves from RLQ to LUQ as the uterus enlarges
What physiological GI changes occur in preg?
o Smooth muscle relaxation by Progesterone
GI – Delayed emptying
Biliary tract – Stasis
Pancrease – Increased risk of pancreatitis
What happens to blood in preg?
o High amount of fibrin deposition at the site of implantation
Increased fibrinogen and clotting factors
Reduced fibrinolysis
o Stasis, venodilation
Why is pro-thrombotic state sometimes disease causing?
o Results in Thromboembolic disease in pregnancy
Cannot give warfarin – Crosses the placenta and is teratogenic
How does anaemia occur in preg?
o Plasma volume increases
o RBC mass also increases, but not to the same degree
o Physiological anamiea
Not a true anaemia, just a mismatch between volume and haemocrit
o Anaemia due to iron and folate deficiency can also occur
Why doesn’t mother attack foetus immunologically?
o Non-specific suppression of the local immune response at the materno-fetal interface
Why is thyroid disease dangerous in perg?
o Graves disease and Hashimoto’s Thyroiditis
Antibodies will cross the placenta and either stimulate TSH receptors on or destroy developing fetal thyroid respectively.
Give three methods of antenatal screening
o History and examination Risk factors – E.g. for gestational diabetes o Blood test Blood group Haemoglobin Infection o Urinalysis Protein
What is pre-eclampsia?
Normal Pregnancy
o Vasodilated
o Plasma-Expanded
o Blood pressure not raised in normal pregnancy
Pre-Eclamptic Pregnancy o Vasoconstricted o Plasma-Contracted o Raised blood pressure o Proteinuria o Pitting oedema
Outline what you discussed with Alex in terms of alveolar ventilation
Respiratory rate does NOT increase to blow off CO2.
Instead, alveolar ventilation rate increases due to tidal volume increase.
Define alveolar ventilation
(Tidal volume - Dead Space) * Respiratory Rate
