6.2: Physiological changes in pregnancy Flashcards
What ‘red flags’ would you be looking for in a history and examination during antenatal screening and what will it help you determine?
- Baby’s risk of acquiring genetic diseases (FH) 2. Maternal lifestyle; smoking and alcohol3. Mother’s medical conditions/system disorder 4. Risk factors for gestational diabetes, preeclampsia, etc.
What are you looking for in an antenatal blood test?
- Blood group and antibody (e.g; Rh factor) 2. Hb - looking for anemia, hemoglobinopathies; SC disease, thalessemias, CF, etc 3. Infections; syphilis, HIV, Hep B, rubella; *only ones that can be treated, managed
What would you check for in an antenatal urinalysis?
- Proteins; the ratio of protein:creatinine can help diagnose preeclampsia 2. Nitrates
Other than taking urinalysis, blood test and history what else would you do during antenatal screening?
Ultrasound to check fetal viability
How is the maternal CVS and blood affected during pregnancy?
Increased blood volume: since CO = SV X HR they all increase
What happens to the systemic vascular resistance and the BP?
Systemic vascular resistance decreases:Progesterone causes vasodilation -> reduced afterload -> decreased BP/hypotension But BP should return to normal during third trimester
How is the preload and afterload affected during pregnancy?
Preload increases, afterload decreases (due to reduced systemic vascular resistance)
What happens to the diaphragm during pregnancy? Which other structure does this affect?
Moves up due to the increased pressure from the uterus, this displaces the heart
When and why can aortocaval compression occur? What advice can be given to prevent consequences of this?
In the third trimester: Compression of the abdominal aorta and IVC due to the gravid uterus when a pregnant women lies on her back -> lie on her L side since IVC is on the R side (so baby’s weight can’t put pressure on it and vessel remains open)
How do endothelia change in pregnancy?
- More permeable (hormones)2. Progesterone causes vasodilation
Name six factors that put some women at risk for preeclampsia. When will signs of it begin to show?
Signs show after 20-21 weeks, but milder case = later diagnosis 1. FH 2. High BMI and first pregnancy 3. Older women having their first pregnancy 4. Multiple pregnancies5. Chronic hypertension6. Any autoimmune condition
What is preeclampsia? How is it caused and what is it characterized by?
No meeting between invading trophoblast cells and the spiralling arteries (maternal vessels)
Imbalance of androgenic and antiandrogenic factors -> widespread endothelial damage -> trophoblast cells fail to invade into the spiral arteries -> uterine vessels stay thick and muscular -> reduced blood flow to baby hindering its growth
Characterized by:
- High blood pressure (rises when there is endothelial damage)
- Signs of damage to another organ system (e.g; kidneys, liver)
How are the kidneys affected during pregnancy/How does the volume that the urinary system has to deal with change?
- Increased volume, GFR and renal plasma
- Filtration capacity stays the same
- Functional renal reserve (ability to increase the renal plasma flow and GFR) decreases because GFR increases
What happens to the blood creatinine as GFR increases in pregnancy and what can be indicated from an abnormal serum creatinine range?
Decreases - if value is abnormal can indicate
preeclampsia or other renal pathologies aggravated during pregnancy
What happens to the bladder and the ureters during pregnancy and why? Name one complication that can arise as a result
Progesterone
- Bladder doubles its capacity
- Ureters dilate - this also predisposes to an ascending bacterial infection
Describe how the effects of progesterone during pregnancy may lead to a series of complications in the urinary system
Urinary stasis -> hydronephrosis -> obstruction and hydroureter -> UTI -> pyelonephritis (inflammation of the kidney typically via bacterial infection) -> irritate uterus -> increased risk of pre-term labor
When would you want to investigate a pregnant woman for a UTI?
Investigate/offer renal scan if woman experiences backache or flank pain and has dysuria
What happens to the chest wall during pregnancy and why? What happens as a consequence of this?
Expanding uterus -> diaphgram elevation -> compensatory increase in; subcostal angle, chest wall circumference, antero-posterior and transverse diameters -> prevents sig. reduction in total lung capacity
*though there is still reduction in functional residual capacity
Define the following and describe how they change in pregnancy A) Vital capacity B) Total lung capacity C) Minute and alveolar ventilation D) Tidal volume E) Respiratory rate
A) Max exhalation after max inhalation; unchanged
B) Vital capacity + residual volume; unchanged
C) Amount of air expelled from alveoli/min; IncreasedD) Volume of air moved in-out of lungs with each ventilation cycle; increasedE) Amount of breaths/min; unchanged
Name two physiological respiration issues pregnant women experience and why they occur.
Physiological hyperventilation
1. increased metabolic CO2 production
- progesterone stimulates respiratory drive -> hyperventilation -> physiological dyspnea
What is a consequence of physiological hyperventilation and how is it compensated for?
Respiratory alkalosis compensated with increased renal bicarbonate excretion
What happens to the PaO2, PaCO2 and FEV1 in pregnant women?
PaO2; increasesPaCO2; decreasesFEV1; unchanged
Why does the vital capacity remain the same in pregnancy?
Expiratory reserve volume reduces to compensate for increased TV and inspiratory reserve volume
What happens to the mothers insulin resistance as the pregnancy progresses? What causes this change?
Maternal peripheral insulin resistance increases -> body switches to gluconeogenesis and alternative fuels
This is achieved via anti-insulin hormones increased during pregnancy; hPL, prolactin, estrogen/progesterone, and cortisol
Why is pregnancy associated with an increased risk of keto acidosis?
Gluconeogenesis can use fatty acids -> increased free fatty acid concentration -> increased lipolysis -> increased Ach and buildup of ketones
What happens to the fasting plasma glucose and post-prandial blood glucose when pregnant?
Fasting - decrease
Post-prandial - increase
Name 6 risk factors for developing gestational diabetes. What would you offer to screen this group of women?
- Immediate FH
- High BMI>30
- Previous gestational diabetes
- Ethnicity; asians and Afro-Caribbeans
- Delivery of a baby>4.5 kilo in the past
- History of PCOS
Offer glucose tolerance test at 26 weeks
Name three risks to the fetus associated with poor control of gestational diabetes and one risk for the mother.
What is provided for mothers with this risk?
- Macrosomic fetus
- Stillbirth3. Increased rate of congenital defects Mother has a high risk of developing type 2 diabetes later so must have annual blood glucose testing
Why are fetuses born to a mother with gestational diabetes so large but born hypoglycemic? What are they at risk of?
Hyperglycemic environment in mother -> fetal pancreas adaptation and overstimulation of insulin an ANABOLIC hormone -> increased production of glycogen and adipose -> macrosomic body
-> babies born into environment with much less glucose than what their bodies are used to -> born hypoglycaemic
Fetus is at risk of respiratory distress syndrome, infections, stillbirth and other congenital defects
What happens to the amount of thyroid hormones during pregnancy and why? Does this change the amount of free T4?
hCG and TSH are structurally similar (on alpha subunit) -> hCG mimics TSH -> increased T3 & T4
But FREE T4 stays the same as levels of thyroid binding globulin (carries it) also increases
Describe 4 physiological changes in the GI system during pregnancy
- Smooth muscle relaxation by progesterone
- Relaxed gut delays transit time/emptying > women may feel constipated, vomit, full quickly
- Biliary tract; stasis
- Pancreas; increased risk of pancreatitis
Why are pregnant women more at risk of having a DVT?
- Pregnancy is a pro-thrombotic state (as there’s more fibrin at implantation site) -> increased fibrinogen and clotting factors and reduced fibrinolysis
- Progesterone -> vasodilation -> blood stasis (furthered by compression of AA and IVC from the gravid uterus)
How does thromboembolic disease commonly present in pregnancy? What can you offer? Warfarin?
Commonly: tender swollen calf, can be SOB and chest pain
Give low molecular weight heparin NOT warfarin as it is teratogenic, can give after birth and mother can breastfeed
Name 8 signs and symptoms for a pulmonary embolism in pregnancy and two additional ones for a massive PE
DPPTTHHC
- Dyspnea2. Palpitations3. Pleuritic chest pain4. Tachycardia5. Tachypnea 6. Hypotension 7. Collapse8. Hemoptysis +cyanosis/hypoxia in a massive PE
Name 6 signs and symptoms for a DVT in pregnancy, is it usually proximal or distal?
Usually proximal
- Unilateral leg pain/tenderness
- Swelling in an extremity - increased calf/thigh circumference 4. Increased temp5. Prominent superficial veins 6. Pitting edema
Explain why pregnant women sometimes experience both physiological and pathological anemia
Physiological: plasma volume increases but the # of RBCs hasn’t as much.
Pathological: iron and folate deficiency or other hemoglobinopathies; sickle cell, thalassemias, etc
How is preeclampsia treated?
- Treat BP
- Monitor the kidney/liver function
- Try extending the pregnancy until mother starts deteriorating (i.e; can’t control BP) or there is risk of damage to fetal growth (latest 34 weeks)
How would you diagnose an asymptomatic pregnant woman with a UTI?
Urinalysis for nitrites
