10. MATERNAL CHANGES Flashcards
1
Q
What are the reasons for maternal changes?
A
- High levels of foetal steroid
- Foetal & maternal demands
- Mechanical displacement
2
Q
What are 6 maternal changes?
A
- Increase in uterus size
- Increased metabolic demands as the uterus grows
- Structural requirements of the foetus
- Removal of foetal waste & delivery of nutrients
- Provision of amniotic fluid
- Preparation for delivery of the foetus & puerpium
3
Q
What 6 systems do maternal changes occur in?
A
- Cardiovascular system
- Gastrointestinal system
- Endocrine system
- Respiratory system
- Energy balance
- Urinary system
4
Q
What 4 classes of hormones are responsible for maternal changes?
A
- Placental peptides
- Maternal steroids
- Placental & foetal steroids - Progesterone, oestradiol, oestriol
- Maternal & foetal pituitary hormones
5
Q
What are the placental peptides?
A
- hCG
- hPL
- GH
6
Q
What are the maternal & foetal pituitary hormones?
A
- GH
- Thyroid hormones - increases to cope with metabollic demand
- CRF (Corticotrophin releasing factor)
7
Q
What 5 features do placental steroid affect?
A
- RAAS
- Respiratory centre
- GI tract
- Blood vessels
- Uterine contractility
8
Q
How does the energy balance change during pregnancy?
A
- There’s an increased need for energy output & storage during pregnancy
- Increased energy output to cope with increase in respiration & CO
- Increased energy to storage for foetus, labour & post-labour needs
9
Q
What happens to basal metabolic rate during pregnancy?
A
- During pregnancy, the basal metabolic rate increases - by 350 kcal a day = mid gestation
- by 250 kcal a day = late gestation
10
Q
How do maternal glucose reserve change in the first trimester?
A
- The number of beta pancreatic cells increase
- Maternal pancreas hypertrophies
- Insulin in plasma increases
- Insulin levels increase in order to overcome insulin resistance caused by maternal pancreas hypertrophy
- Glucose stores are used by muscle, so serum glucose levels fall
11
Q
How do glucose levels change in the 2nd trimester?
A
- Increased need for glucose in 2nd trimester
- Glucose is actively transported across placenta to provide foetal energy source
- Insulin resistance increases due to hPL
- Insulin resistance = less glucose in stores
- Glucose serum levels rise but ca cause gestational diabetes
12
Q
What causes insulin resistance in the first & second trimester?
A
- First trimester = hypertrophy of maternal pancreas
- Second trimester = hPL
- Insulin resistance means insulin is unable to control glucose & cause storage. Decreases the rate of glucose uptake, meaning less glucose is stored & more is in the serum
13
Q
What is gestational diabetes?
A
- Gestational diabetes occurs when the body can’t make enough insulin during pregnancy to control blood glucose levels
- Body cannot overcome the insulin resistance caused by pregnancy. Insulin levels need to rise to overcome the insulin resistance
- However, some women already have insulin resistance prior to pregnancy. So the insulin resistance from pregnancy exacerbates their risk to gestational diabetes
14
Q
Which hormones act on RAAS during pregnancy?
A
- E2 - oestrogen & oestradiol
- Progesterone
15
Q
What’s the effect of E2 & progesterone on pregnancy?
A
- Increased sodium retention
- The threshold for thirst is lowered = more water consumption
- Decreased plasma oncotic pressure
- Sodium retention leads to water retention
16
Q
How much water weight is gained?
A
8.5L
17
Q
Where is the water gain redistributed to?
A
- Placenta
- Amniotic fluid
- Uterine muscle
4, Mammary gland - Plasma volume (main source)
18
Q
What are the consequences of the increase in body water during pregnancy?
A
- Oedema in lungs, connective tissue, ligaments, swollen ankles & legs
- Physiological anemia of pregnancy - increase in plasma volume proportional to RBC can cause anemia
19
Q
What happens to respiration during pregnancy?
A
- Respiration rate increases during pregnancy to increase oxygen consumption
20
Q
How does respiration rate increase during pregnancy?
A
- Sensitivity to CO2 (H+ ions) increases to increase oxygen consumption
- Thoracic ribcage displaced outwards & upwards to expand leading to increase in thoracic volume
- Longer & deeper breaths to increase minute volume by 40%
- Arterial O2 (PO2) increases, whilst arterial CO2 (PCO2) decreases
21
Q
How does an increase in respiration facilitate foetal gas exchange?
A
- Increase in oxygen & decrease in CO2 favours foetal gas exchange
- Maternal oxygen is higher so diffuses down concentration gradient into foetus
- Foetus CO2 is lower so diffuses out into maternal circulation to be removed
22
Q
What happens to maternal blood volume?
A
- Increase in plasma volume
- Increase in RBC mass
- But increase in plasma volume is much greater, so the ratio of plasma volume to RBC can cause physiological anemia of pregnancy
- Increased efficiency of iron absorption from the gut/GI
23
Q
What’s the effect of maternal blood becoming hypercoaguable?
A
- White blood cells & clotting factors undergo changes making the blood HYPERCOAGUABLE
- There are higher levels of fibrinogen in hypercoagulable blood
- Blood becomes hypercoagulable for placental separation & to cope with demands of child
24
Q
What is a risk of the blood becoming hypercoaguable?
A
- Risk of thrombosis is high
- PE or DVT
25
What happens to foetal blood content?
- Increased haemoglobin
| - Different type of haemoglobin
26
What's the difference between foetal & maternal hemoglobin?
- Foetal haemoglobin has a higher affinity for oxygen/greater binding than maternal Hb
- Foetal Hb binds to O2 given up by maternal Hb
27
What's the consequence of smoking on foetal-maternal gas excahnge?
- Smoking can increase maternal carboxyl Hb which is more permanent
- Reduces the increased oxygen binding
- Leads to foetal hypoxia
28
What happens to heart sounds during pregnancy?
- Slow murmur due to increased volume of blood flowing through the heart
- S1 & S3
29
What happens to CO during pregnancy?
- Increase in CO for maternal muscle & foetal supply
- CO= HR X SV
- Both HR & SV also increase, but increase in CO is mainly due to SV
- CO begins to increase at 3 weeks & peaks at 28 weeks
30
What happens to TPR during pregnancy?
- TPR decreases
WHY?
- Increase in CO
- Vasodilation caused by sex steroids specifically progesterone
- BP = CO X TPR
- Blood pressure also drops
- Formation of new blood vessels to cope with heat loss - neoangenesis
31
What are the two main consequences of GI maternal changes?
1. Constipation
| 2. Acid reflux
32
What are the three main maternal effects on the GI tract?
1. Increase in appetite & thirst due to progesterone
2. Reduced GIT motility
3. Relaxation of LOS
33
How can pregnancy cause constipation?
- Progesterone relaxes the smooth muscles
- Reduced GI tract motility occurs
- Constipation
34
How can constipation be treated?
Lactulose
35
How can pregnancy cause acid reflux?
- Progesterone relaxes smooth muscles
- LOS (lower oesophageal sphincter) relaxes causing acid reflux of gastric conetnts
- Also caused by large uterus pressing against GI
- Heart burn
36
Why is folic acid important in pregnancy?
- Folic acid is involved in DNA production, growth, blood cell production in the uterus, placenta & foetus
- Folic acid deficiency linked to Spina bifida neural tube defect
37
How much folic acid should pregnant women take?
- 400mcg/day 3 months before pregnancy leading up to Week 12 of pregnancy
- 5mg in high risk women
38
Why do pregnant women have an increased UTI risk?
- Progesterone acts on smooth muscles so it dilates the ureter, kidney & bladder
- Urinary tract is dilated in a dilated system
- Some urine may be retained in bladder = UTI
39
What happens to GFR during pregnancy?
- Increased blood flow to the kidney so increased GFR
- Increased clearance of creatinine, urea, uric acid
- GFR reference values used for pregnant women should be adjusted
40
Why do pregnant women experience urinary frequency?
- Early pregnancy = uterus is enlarging but it's still within the pelvis, so it compresses the bladder leading to urinary frequency
- 2nd trimester/mid pregnancy = uterus is lifted out of pelvis, decreased pressure on bladder so micturition is normal
- End of pregnancy = head of foetus descends into pelvis, more pressure = urinary frequency
41
What happens to the uterus?
- Size of uterus increases
- Increase in muscle mass & blood flow to placenta & uterus
- Isthmus becomes softened & elongated
- Lower uterine segment acts as funnel for baby's head
- Lower segment formed from isthmus which si less muscular
42
What happens to the cervix?
- Cervix increases in vasculature
- Tissue softens from 8 weeks
- Changes in connective tissue in preparation for expansion
- Proliferation of glandular tissue
- Progesterone forms a thick mucosal plug protecting baby's head
43
What happens to the body post-labour?
1. Fall in sex steroid level upon delivery & removal of placenta
2. Most endocrine related changes returns to normal
- CO returns to normal after 2 weeks
3. Uterine muscle shrinks rapidly & loses oedema. Contracts slowly but doesn't return to pre-pregnancy size. Uterus descends to pelvis by day 10
4. Removal of sex steroids allows increased prolactin to act on the breast. Suckling of baby allows lactation
