Maternal changes in pregnancy Flashcards
1
Q
What are 6 events that occur to cope with the changes during pregnancy?
A
- increase in size of uterus
- increased metabolic requirements of uterus
- structural + metabolic requirements of fetus
- removal of fetal waste products
- provision of amniotic fluid
- preparation for delivery + puerperium (first 6 weeks)
2
Q
In which systems do major changes occur?
A
- energy balance
- respiratory
- cardiovascular
- gastrointestinal
- urinary
- endocrine
3
Q
Which hormones cause most of the changes?
A
- maternal steroids - placenta takes over ovarian (CL) production around week 7
- placental peptides - hCG, hPL, GH
- placental + foetal steroids - progesterone, oestradiol, oestriol
- maternal + fetal pituitary hormones - GH, thyroid hormones, prolactin, CRF
4
Q
Where is the effect of placental steroids?
A
- renin-angiotensin system
- respiratory centre
- GI tract
- blood vessels
- uterine myometrial contractility
5
Q
What is the total weight gain during pregnancy?
A
-
12.5-13kg
- fetus + placenta = 5kg
- fat + protein = 4.5kg
- body water = 1.5kg
- breasts = 1kg
- uterus = 0.5-1kg
- ideally keep to less than 13kg
- failure to gain or sudden change needs monitoring
6
Q
Why will a mother need to increase energy?
A
- output: to cope w/ increased respiration + cardiac output
- input: for fetus, labour + puerperium
7
Q
Why is there a gain in fat and protein stores?
A
- 4-5kg
- increased consumption + reduced use
- mainly laid down in anterior abdominal wall
- utilised later in pregnancy + puerperium
8
Q
What happens to the basal metabolic rate?
A
rises by:
- 350 kcal/day mid gestation
- 250 kcal/day late gestation
- usage: 75% fetus and uterus, 25% respiration (H&L)
- 9 calories = 1g fat, therefore 40g fat for 350kcal ie 1 large mars bar
9
Q
When is glucose important in pregnancy?
A
Need increased levels in blood in 2nd trimester
10
Q
How does the glucose get to the fetus?
A
- active transport across placenta as fetal energy source
- fetus stores some in liver
11
Q
What happens in the 1st trimester with glucose?
A
- maternal reserves
- pancreatic B-cells inc in number
- plasma insulin increases so more goes into tissues
- laid down as stores + used by muscle
- fasting serum glucose decreases
12
Q
What happens in the 2nd trimester with glucose?
A
- fetal reserves
- hPL causs insulin resistance
- ie less glucose into stores
- increase in serum glucose
- more crosses placenta
- but can cause diabetes
13
Q
What are the reasons for increased water wain?
A
- E2 and P act on renin angiontensin system
- fluid retention possible due to sodium retention
- resetting of the osmostat
- decrease thirst threshold
- decrease in plasma oncotic pressure (albumin)
14
Q
How is oxygen consumption increased?
A
- stimulated by E2 and P
- increases respiratory centre sensitivity to CO2
- thoracic anatomy changes.. ribcage displaced upwards, ribs flare outwards
- breathe more deeply
- minute volume increases 40%
- arterial PO2 increases 10%, PCO2 decreases 15-20%
- this facilitates placental gas transfer
15
Q
What happens to the maternal blood content?
A
- Hb concentration will measure slightly lower due to higher intravascular fluid (haemodilution)
- red cell mass should rise (18%)
- placenta in fetuses are also iron-hungry
- increaseded efficiency of iron absorption from gut
- white cells increase
- blood becomes hypercoagulable = inc fibrinogen for placental separation, but inc risk of thrombosis
