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77 Cards in this Set

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  • Back
When do most women begin to report symptoms of pregnancy?
By the end of the sixth week after the last menstrual period.
How is increased availability of precursors for hormone production and foetal-placental metabolism achieved?
Increased availability of metabolic substrates and hormones is achieved by increases in dietary intake, as well as endocrine changes that increase the availability of substrates like glucose.
How is transport capacity improved?
Increased cardiac output
How is the maternal foetal-exchange managed throughout gestation?
The placenta regulates maternal-foetal exchange by 10-12 weeks gestation, but transfer occurs though other mechanisms before this.
How are additional waste products disposed of?
Disposal of heat - peripheral vasodilatation.
Disposal of CO2 - ventilation.
Disposal of metabolic byproducts - renal filtration.
Why does the maternal blood volume expand during pregnancy?
To allow adequate perfusion of vital organs, including placenta and foetus.
To anticipate blood loss associated with delivery.
In what compartment does the maternal blood volume increase?
It increases in both the intracellular and extracellular, but is more marked in the ECF, especially the plasma volume.
How much does total body water increase during pregnancy?
6.5 - 8.5kg.
Broadly speaking what are the consequences of fluid retention during pregnancy?
The concentrations of certain substances in circulation decrease (e.g. Hb, HCT, albumin), whereas there is a marked increase in haemodynamics (CO and GFR).
What is the mechanism behind fluid retention in pregnancy?
Changes in RAAS system result in active sodium reabsorption in the renal tubules. Sodium is sequestered within the foetal tissues.
What factors contribute to fluid retention?
1. sodium retention
2. resetting of osmostat (plasma osmolatlity decreases by 10mOsmol/kg)
3. decreased thirst threshold
4. decreased plasma oncotic pressure (due to decreased albumin concentration)
What causes the physiological anaemia of pregnancy?
1. Increased plasma volume
2. Increased erythrocyte mass
3. Transfer of iron stores to the foetus
What is the mean haemoglobin concentration for a pregnant woman?
The mean Hb concentration falls from 13.3g/dL in a non-pregnant state to 10.9g/dL at the 36th week of pregnancy.
What is a normal pregnancy haematocrit?
32-34%, which is lower than non-pregnant values.
Do pregnant women require increased amounts of iron?
Yes. Even though there is increased absorption of dietary iron from the gut, women who do not take supplementary iron during pregnancy show a reduction in bone marrow iron and are still low six months after delivery.
What happens to renal clearance of folic acid during normal pregnancy?
What happens to plasma folate concentrations in normal pregnancy?
They fall. However, red cell folate concentrations do not decrease to the same extent.
What happens to the platelet count during pregnancy?
The maternal platelet count usually remains stable, though may slightly decrease due to increased platelet aggregation, and then increase in the first week post-partum, putting pregnant women at risk of VTE.
What happens to the procoagulant factors during pregnancy?
They increase. Almost all factors increase, indlucing VII, VII, IX, X, XII and fibrinogen, and vWF (which is a crrier for factor VIII)
What happens to plasma D-dimer concentration during pregnancy and what impact does this have on VTE?
Maternal plasma D-dimer concentration increase from conception until delivery, and therefore limits the use of D-dimer testing to rule out VTE.
Why and how is the fibrinolytic system activated during pregnancy?
It is activated to counterbalance the increase in coagulation factors. There is increase in D-dimers, fibrin degradation products, plasminogen and activators of plasminogen.
Why is hypercoaguability important for delivery?
At term, 500 mL of blood flows through the placental bed each minute. Without effective rapid haemostasis, women would die from blood loss.
How is haemostasis achieved at delivery?
1. Myometrial contractions first compress the blood vessels supplying the placental bed.
2. Fibrin depostion over the placental site (to form clot).
What happens to plasma protein concentrations during pregnancy?
They are decreased, especially albumin.
What are the effects of the decreased plasma protein concentration during pregnancy?
The plasma oncotic pressure is reduced.
The peak plasma concentration of drugs which are protein bound is reduced. Some drugs may be less effective.
What happens to the concentration of serum creatinine, uric acid are urea concentrations?
They are all reduced during normal pregnancy, although the renal handling of uric acid changes in late gestation, resulting in increased reabsorption.
How are LFTs affected during pregnancy?
ALP levels increase due to production of placental ALP. ALT and AST are often lower.
What is the reference value for haemoglobin in normal pregnancy?
11.0 g/dL
What is the reference range for HCT in normal pregnancy?
What is the reference value for albumin in normal pregnancy?
23 - 28 g/L
What problems related to brain function do women report during pregnancy?
Attention, concentration and memory deficits during pregnancy and the early post-partum period.
Do pregnant women require the same amount of local anaesthetic in the epidural/intrathecal space as non-pregnant women?
No, they require less.
Why do pregnant women have an increased tolerance for pain?
Due to increased serum levels of beta-endorphins and activated spinal cord kappa-opiate receptors.
How does perception of odours change during pregnancy?
Aversion to some odours is common in early gestation. Olfactory sensitivity than decreases during the third trimester.
What happens to the corneal sensitivity in most pregnant women?
Decreases while preganant and the returns to normal by 8 weeks post partum.
What can lead to an increase in corneal thickness in the pregnant woman?
Decreaed tear production
Why may pregnant women be intolerant of contacts?
Because of the changes in cornea and tear film.
What can cause a transient loss of accommodation during pregnancy?
The curvature of the crystalline lens can increase causing a myopic shift in refraction and transient loss of accommodation.
Why are pregnant women prone to nose bleeds?
The vascularity of the respiratory tract mucosa increases and the nasal mucosa can become oedamatous and brone to bleedings.
When does ventilation began to increase significantly?
At around 8 weeks of gestation, most likely in response to progesterone-related sensitisation of the respiratory centres to carbon dioxide, and also the increased metabolic rate.
What is the result of the enlarging uterus elevating the diaphragm?
Decreased residual volume and decreased functional residual capacity. FRC is further decreased when supine.
What is the effect of relaxin upon the rib cage?
It allows the ligaementous attachments of the ribcage to relax, increasing the subcostal angle and changing thoracic anatomy.
What is the result of the increased 2,3-DPG concentration in maternal erythrocytes?
2,3-DPG preferentially binds to deoxygenated haemoglobin and causes the release of oxygen from red cells, increasing the availability of oxygen to the tissues.
How is foetal haemoglobin different from adult haemoglobin and why is this important?
Foetal haemoglobin has two beta chains while adult haemoglobin has two gamma chains. Oxygen binds preferentially to beta chains, favouring oxygen transport to the foetus.
What happens to blood gas and acid-base levels during pregnancy?
Decreased carbondioxide, increased oxygen, slightly altered pH, increased bicarbonate excretion, increased oxygen availability to tissue and placenta.
How does pregnancy mimic cardiac disease?
Breathlessness: due to elevation of the diaphragm, adjustments of lung volume and increased minute ventilation.
Peripheral oedema: due to increase in total body sodium and water and venous compression by uterus.
Syncope: due to venous compression by uterus impeding blood return.
Palpitations due to sinus tachycardia.
Does the heart rate increase or decrease during pregnancy?
Increases by 10 - 20%.
Does the stroke volume increase or decrease during pregnancy?
Increases by 10%.
Elevated at the onset of labour to 7.0 L/ min, increases by 30% in the final stages.
Each uterine contraction squeezes 300 - 500 mL of blood into the maternal circulation.
The CO remains elevated for the first two days post-partum and then falls rapidly for two weeks after delivery.
Does the CO increase or decrease during pregnancy?
Increases by 30 - 50%.
What happens to the mean arterial pressure during pregnancy?
Decreases by 10%.
What happens to the pulse pressure during pregnancy?
It decreases.
What happens to peripheral resistance during pregnancy?
It decreases by 35%.
What ausculatory changes can be heard in pregnancy?
Loud first heart sound, sometimes split.
Third heart sound sometimes heard at 20 weeks.
Ejection systolic murmur heard in 96% of normal pregnant women.
What are the GIT changes in pregnancy, in terms of oral, liver, gut?
Oral: pregnancy gingivitis (erythema, oedema, hyperplasia, increased bleeding); increased tooth mobility.
Gut: reflux oesophagitis due to LOS relaxation caused by elevated progesterone levels; constipation delayed gastric emptying and increased stomach volume; increased risk of aspiration of gastric contents when anaethetised after 16 weeks.
Liver: hyperoestrogenic state can cause telangiectasia and palmar erythema; raised ALP in third trimester; increased production of fibrinogen and clotting factors; hypercholesterolaemia.
What are the renal changes in pregnancy?
Increase in kidney size.
Dilated renal pelvis and ureters.
Increased blood flow to kidneys.
Increased GFR.
Increased renal plasma flow.
Increased clearance of most substances.
Decreased plasma creatinine, urea, urate.
Glycosuria is normal.
Is glycosuria normal or abnormal during pregnancy?
It is very common during pregnancy and does not relate reliably to disorders of carbohydrate metabolism.
What happens to the uterus during pregnancy?
Increased blood flow (700ml/min at term).
Increased weight (50-60g before pregnancy, 1kg by term).
Hypertrophy and later stretching of the uterine arteries.
Development of intercellular gap junctions between myometrial cells.
What is the effect of oestrogen on the uterus?
Mediates the adaptation of the uterine smooth muscle to pregnancy. Induces hypertrophy and hyperplasia.
What is the effect of progesterone on the uterus?
Induces hypertrophy and hyperplasia.
Helps maintain low myogenic tone in the uterine vessels.
What are Braxton-Hicks contractions?
Painless contractions that are noticed in the second half of pregnancy. They are due to the maturation of the gap junctions between myometrial cells.
What colour is the cervix during pregnancy?
It looks bluer due to increased vascularity.
How does the cervix constituency change during pregnancy?
What is the ectropion and what causes it during pregnancy?
The growth of the columnar epithelium of the cervical canal. This becomes visible on the ectocervix and is called the ectropion, which is prone to contact bleeding.
Due to the effect of oestradiol.
What helps to soften the cervix during late gestation?
Prostaglandins induce a remodelling of the cervical collagen.
Collagenase from leukocytes also softens cervix.
What happens to the vaginal epithelium under the influence of oestrogen during pregnancy?
It becomes more vascular and there is increased desquamation causing increased vaginal discharge.
What is the effect of oestrogen on the breasts during pregnancy?
Increases the number of glandular ducts.
What is the effect of progesterone and human placental lactogen (hPL) on the breasts during pregnancy?
Increase the number of gland alveoli.
What is the role of prolactin during pregnancy?
Stimulates milk secretion and during pregnancy prepares the alveoli for milk production.
Why doesn't the increased amounts of prolactin during pregnancy cause lactation?
Becuase it is antagonised at an alveolar receptor level by oestrogen. The rapid fall in oestrogen after delivery removes the inhibition and allows lactation to begin.
What is the effect of suckling?
Suckling stimulates the anterior and posterior piruitary to release prolactin and oxytocin, respectively.
What is the role of oxytocin?
Oxytocin causes contraction of the myoepithelial cells surrounding the glandular ducts, squeezing milk towards the nipple.
Also facilitates maternal-child bonding.
Why is there a fall in TSH and a rise in free T4 during the first trimester of pregnancy?
This is because hCG has subunit homology with TSH, therefore supressing maternal TSH production during the first trimester when hCG levels are highest.
With advancing gestation, the free T4 concentration starts to fall...
How much weight can a women with pre-pregnancy BMI of <20 be expected to gain to have a healthy baby?
12.5 - 18kg.
How much weight can a women with pre-pregnancy BMI of 20 - 26 be expected to gain to have a healthy baby?
11.5 - 16kg.
What are the changes in carbohydrate metabolism during pregnancy?
First half: fasting plasma glucose reduced with no change in insulin levels.
Second half: increased in glucose values despite significant increases in plasma insulin concentrations. Suggests insulin resistance.
May allow shunting of nutrients to the foetus?
Why is it bad to be vitamin D deficient during pregnancy?
Foetal demand for calcium is substantial to ensure skeletal development.
Vitamin D assists in gut calcium absorption.
What are the skin changes during pregnancy?
Increased sebaceous gland activity.
Striae gravidarum.