Maternal changes in pregnancy Flashcards
1
Q
Why are there maternal changes in pregnancy?
A
- high levels of steroids
- mechanical displacement
- foetal requirements
2
Q
What are the main events that cause the need for maternal changes?
A
- increase in size of the uterus
- increased metabolic requirements of uterus
- structural and metabolic requirements of foetus
- removal of foetal waste
- provision of amniotic fluid
- prep for delivery and puerperium (6 weeks after childbirth)
3
Q
What are the 6 systems that the changes occur?
A
- energy balance
- respiratory system
- CVS
- GI system
- urinary system
- endocrine system
4
Q
Which are the main hormones that cause the changes?
A
- maternal steroids - placenta takes over ovarian (CL) production around week 7
- placental peptides - hCG, hPL (human placental lactogen), GH
- Placental and foetal steroids - progesterone, oestradiol, oestriol
- maternal and foetal pituitary hormones - GH, TH, PRL, CRF
5
Q
What is the total gain in weight in pregnancy?
A
- Foetus plus placenta = 5kg
- Fat and protein = 4.5kg
Body water = 1.5kg - Breasts = 1kg
- ## Uterus = 0.5-1kgAltogether = 12.5-13kg
6
Q
How does the mother increase blood glucose levels in the 2nd trimester?
A
- 1st trimester - increase maternal reserves
- pancreatic beta cells increase in number, increasing plasma insulin, storing more glucose into tissue
- 2nd trimester - increase foetal reserves
- hPL causes insulin resistance, meaning that less glucose is taken into stores
- causes an increase in serum glucose so more can cross the placenta to the foetus
7
Q
What problems can mothers get from the water gain?
A
- oedema in lungs, connective tissue (causing backache) and ligaments (causing softening and stretching)
- EC water can compress the carpal tunnel causing pain in the hand, and the lateral nerves causing leg pain
- there is a rise in venous pressure (maybe as high as 24mmHg), which can lead to capillary leakage, especially in the lower body, causing things like swollen ankles
8
Q
How does oestrogen and progesterone affect respiration?
A
- stimulate the respiratory centre, increasing its sensitivity to CO2
- therefore in early pregnancy, the mother appears to be breathless as she is pumping out CO2 for the foetus too
- minute volume increases 40%
- lowered PCO2 on the maternal side of the placenta facilitates the transfer of CO2 from foetus to mother
- To maintain the pH, bicarbonae ions are reduced
- arterial PO2 rises 10 %
- anatomically, the rib cage is lifted and diameter increased, the ribs are flared too, which increases the subcostal angle from 68 to 103 degrees at term
9
Q
How does maternal blood change during pregnancy?
A
- plasma vol increases by 45% and red cell mass increases by 18%
- increase in WBCs (mainly neutrophils)
- increase positively correlated with size and number of foetuses
- increased efficiency of iron absorption from gut
- increase in factors VII, VIII and X (induce coagulation) and a decrease in factors IX and XIII (fibrinolytic) - causes an increase in fibrinogen and so an increased ability to clot
- changes all gradually disappear after birth and delivery of placenta (the events the hypercoagulable state was designed to cope with)
10
Q
Why are there differences in foetal and maternal blood?
A
- HbF has a much higher affinity for oxygen than maternal
- when the two circulations are close therefore, ie in the placenta, oxygen is readily given up from the maternal to foetal circulation
- the transfer is also assissted by the lower acidity of the foetal tissues, which in turn results in the low pH in the placenta
11
Q
How can smoking affect the foetus?
A
Smoking increases maternal carboxy-Hb, which is more permanent and reduces the increased binding - leads to foetal hypoxia
12
Q
What changes occur to the heart?
A
- The expanding uterus pushes the heart round and changes ECG and heart sounds
- Increased CO, HR and SV - needed for maternal muscle and foetal supply
13
Q
What changes occur to the blood vessels?
A
- increased CO and vasodilation by steroids - reduces TPR
- Progesterone is a vasodilator and oestrogen increases NO production
- Increased flow to uterus, placenta, muscle, kidney, skin
- neoangiogenesis - including extra capillaries in the skin (spider nevi) to aid heat loss
14
Q
How does pregnancy affect the GI system?
A
- high levels of progesterone reduce motility of the GIT and relax the lower oesophageal sphincter, leading to constipation and acid reflux
- in later the pregnancy, the larger uterus also causes acid reflux
- Steroids produced also increase appetite and thirst
15
Q
What is Mendelson’s syndrome?
A
- Gastric acid reflux during labour when GIT motility stops will cause vomiting into the lungs - fatal
- no food should be eaten during labour and the woman can be treated with alkaline to reduce acidity and H2 blockers to prevent acid secretion
