Maternal changes in pregnancy Flashcards
Which hormones cause maternal changes in pregnancy?
Placental Peptides: hCG, hPL, GH
Maternal Steroids
Placenta & Foetal Steroids: progesterone, oestrodiol, oestriol
Maternal & Foetal Pituitary Hormones: GH, thyroid hormones, prolactin, CRF
Describe the energy balance during pregnancy.
Increased energy output
-to cope with increased respiration and cardiac output
Increased energy storage
-for foetus, labour and puerperium (breast-feeding is calorific)
Describe the Basal metabolic rate in pregnancy.
rises by 350 kcal/day mid-gestation
rises by 250 kcal/day late-gestation
75% of this increase is for foetus and uterus, 25% for respiration
Describe the glucose changes during pregenancy.
1st trimester
- pancreatic β-cells increase producing more insulin
- plasma glucose decreases
2nd trimester
-hPL and oestrogen cause insulin resistance, increasing plasma glucose
What is Gestational diabetes?
diabetes during pregnancy
-common in 2nd trimester due to insulin resistance from hPL and oestrogen
What is the Effect of pregnancy on total water gain?
oestrogen and progesterone affect the renin/angiotensin axis by causing:
- thirst
- fluid retention
- sodium retention
- decrease in plasma oncotic pressure (albumin levels drop)
- resetting of osmostat
- total increase in plasma volume and this will be distributed to different areas
- very common for some of it to end up in oedema
How is Respiration affected during pregnancy?
oestrogen & progesterone affect repiratory centre in the brain:
- increased sensitivity to CO2
- women breathe more deeply
- increase in minute volume by 40%
- therefore increase in arteriole PO2 (10%) and decrease in PCO2 (15-20%)
Describe the Gas transfer between mother and foetus.
high maternal PO2 and low maternal PCO2 facilitates gas transfer:
- high O2 causes O2 transfer to foetus
- low CO2 causes foetal CO2 (waste) to be transferred back into mum, providing foetal protection
What is the Effect of pregnancy on maternal blood?
40-50% increase in plasma volume
20% increase in red blood cells
HAEMODILUTION
-more plasma serum and less red blood cells (apparent anaemia)
- increase in white blood cells and clotting factors; blood becomes hypercoagulable, increasing risk of thrombosis
- increased efficiency of iron absorption from gut
Describe the foetal blood during pregnancy.
increased Hb with altered type (HbF)
- increased O2 affinity than maternal Hb (HbA)
- therefore oxygen given up by HbA to HbF
foetus has higher Hb concentration than mother
What is the effect of smoking on the foetus?
causes foetal hypoxia because more maternal carboxy-Hb, stopping transfer of oxygen to foetus because carboxy-Hb is more permanent
Descibe the Cardiovascular changes in pregnancy.
Changes in ECG and heart sounds
- expanding uterus pushes heart around
- murmurs develop due to high blood flow
Increased Cardiac Output
- increased heart rate and stroke volume
- for maternal muscle (uterus), skin, kidneys and foetal supply across placenta
Blood Vessels
-lower blood pressure despite greater CO due to a greater reduction in TPR by vasodilation
Describe the Effect of steroids during pregnancy on GI Tract.
- increased appetite and thirst
- reduced GIT motility (causes constipation)
- relaxes Lower Oesophageal Sphincter (causes acid reflux)
What is folic acid used as a supplement for?
DNA production
growth
blood cells
Which neural defect is folic acid deficiency linked to?
neural tube defect called spina bifida
Describe the Urinary system changes in pregnancy.
smooth muscle relaxation in urinary tract:
- bladder
- ureters
- collecting systems in kidney
increased diuresis due to increased CO
increased clearance of creanine, urea, uric acid
Why are pregnant women more prone to UTIs?
due to urinary stasis from smooth muscle relaxation
Describe the Micturition in pregnancy.
in 1st trimester, uterus enlarges compressing the bladder and increasing urinary frequency
in 2nd trimester, uterus is lifted out of the pelvis and there is less pressure on bladder, normal micturition
in 3rd trimester foetus head compresses bladder and increases urinary frequency
Explain the Changes in uterine size during pregnancy.
hypertrophy: huge increase in muscle mass
huge increase in blood flow
*placenta+uterus receive 1/6 of total blood supply (hence a lot of bleeding during C-section)
Describe the Changes in uterus during pregnancy.
isthmus (lower part of the uterus) expands and is less muscular and more fibrous, forming the lower uterine segment, which acts as a funnel to allow baby to come down
top of the uterus still muscular to push baby down
Where is the incision made during a C-section?
lower segment C-section because there is less bleeding when there is less muscle and more fibrous structures
Describe the Changes in the cervix during pregnancy.
- increase in vascularity
- connective tissue softens from 8 weeks to begin gradual preparation of expansion
- proliferation of mucosal glands, greatly increasing mucosal production (protective, anti-infective)
Cervix during labour is softened by…
inflammatory mediators and prostaglandins
Describe the Maternal changes after pregnancy.
Returns to normal:
- dramatic & rapid fall in steroids on delivery of placenta
- most endocrine driven changes return to normal rapidly
- uterine muscle rapidly loses oedema but contracts slowly and never returns to pre-pregnancy size
- removal of steroids (oestrogen and progesterone) permits action of raised prolactin on breast for breastfeeding
