Physiology in pregnancy Flashcards
Why are pregnant people more prone to back pain?
Their centre of gravity has changed, so they need to lean back more. This changes the curves of the spine.
Which hormones affect the connective tissue? Which tissue is most affected?
Relaxin (produced during pregnancy)
Oestrogen and progesterone.
Symphysis pubis and sacroiliac joints
How does relaxin, progesterone and oestrogen change the pubic symphysis?
The gap increases from 4-5mm by another 3mm.
When does the pubic symphysis joint loosen?
10 weeks, should return to normal 4-12 weeks post party.
What is the increased load on the hips?
By term the load has increased by 2.8
What is pubic symphysis dysfunction?
This is pain in the pelvic region, caused by stiffness or unequal movement on the joints. It is painful but not harmful to baby.
What does human placental lactose do?
Produced by the placenta:
- decreases maternal insulin sensitivity
- decreases maternal glucose utilisation
To ensure there is enough energy for the baby.
What is the normal weight gain for pregnancy?
10-14kg.
Lipid storage is increased.
Why are lipids essential to the foetus?
For organogenesis.
When is fatigue most likely to affect a women during pregnancy?
1st trimester (due to change in hormones)
3rd trimester (due to heavier and harder workload)
Which hormone relaxes the lower oesophageal sphincter?
Progesterone. gastric emptying is also delayed.
Why is general anaesthetic a higher risk in pregnancy?
Due to the relaxation of the lower oesophageal sphincter - the risk of aspiration is increased.
Which vessel dues the uterus tend to compress?
The inferior vena cava, leads to oedema or fainting if woman lies on her back.
What condition is oedema a sign of?
Pre-eclampsia. Its also very often normal.
How many women experience oedema during pregnancy?
80%
What is pre-eclampsia?
When you have high blood pressure and traces of protein in your urine.
What changes occur to the areola in pregnancy?
it gets bigger and more pigmented.
Montgomery tubercles appear (they are always on the areola but not normally visible)
What is the physiology behind oedema in pregnancy?
increased sodium and water retention.
How many Montgomery tubercles are found on the areola?
0-40
What do the Montgomery tubercles do?
They produce some breast milk but mainly produce an oil which prevents bacterial infections.
They contain milk glands and sebaceous glands.
What happens to the thyroid gland during pregnancy?
thyroid binding globulin, T3 and T4 all increase. This evens out so the levels of free T3 and T4 remain the same.
Why might the thyroid gland hypertrophy?
to try and absorb enough iodine.
How common is overactive thyroid in pregnancy?
1 in 500
mostly caused by graves disease. the antibodies that cause graves can cross the placenta and cause foetal and/or neonatal hyperthyroidism.
How long does the foetus rely on the mothers thyroid function?
until 12 weeks gestation.
Hypothyroidism occurs in 1% of pregnancies.
Why do some auto immune conditions improve during pregnancy?
Because the body becomes more immunosuppressed. This allows for the foetus not to be rejected.
What is the leading cause of indirect maternal death?
Cardiac Disease.
How much does circulating blood volume increase?
50-70%
How much does the haemoglobin increase?
40%
Why is anaemia common in pregnancy?
Blood volumes increase more than haemoglobin does - causing dilution of haemoglobin.
Where is there increased blood flow during pregnancy?
Kidney (60-80% ^)
hands and feet
nasal mucosa (^risk of nose bleeds)
When is the systemic vascular resistance at its lowest?
20-32 weeks.
How much does cardiac output increase?
30-50%
How much does the HR increase?
By term, the HR is usually 10-20 beats higher.
How much does oxygen consumption increase?
20-30% - the myocardium needs more oxygen.
What should you never do to a pregnant patient?
Lie them flat.
They will lose 25% of cardiac output - faint.
How must a pregnant person be resuscitated?
On a left lateral tilt
or with the uterus manually displaced
What is a perimortem Cesarian section?
Emptying of the uterus immediately during cardiac arrest to try and save the mother and foetus.
What is auto transfusion of contractions?
This is when the uterus contracts and transfers blood from the uterus into the maternal circulation.
How much blood can be transferred to the maternal circulation during uterine contractions?
Up to 500mls.
What effect does the pain of pregnancy have on the heart rate and cardiac output?
They both increase because pain causes an increase in circulating catecholamines.
How much does cardiac output increase during pregnancy?
10%
How much does cardiac output increase immediately after pregnancy?
up to a further 60-80%, due to the release of pressure on the inferior vena cava and the lack of blood needing to supply the uteroplacental unit.
How long does cardiac output take to return to normal after labour?
About 1hr.
How much do blood volumes decrease 3 days post delivery?
10%
What happens to the blood pressure after delivery?
It initially falls
then increases again 3-7 days after birth
then returns to PRE-pregnancy levels by 6 weeks
Why does systemic vascular resistance drop during pregnancy?
- Due to blood travelling away to the uteroplacental unit
- theres an increase in circulating vasodilators
How long after pregnancy does heart rate take to return to pre-pregnancy levels?
2 weeks
How long after pregnancy does systemic vascular resistance take to return to pre-pregnancy levels?
2 weeks
What happens to carbon dioxide levels in pregnancy?
The mothers tidal volume and minute ventilation increases so carbon dioxide decreases.
They are in compensated respiratory alkalosis.
What affect does progesterone have on asthma?
It acts as a bronchodilator, some peoples asthma improves during pregnancy.
What is considered normal haemoglobin levels at 28 weeks?
105g/L
What is the physiological anaemia of pregnancy?
Plasma volume increases to a larger extent than haemoglobin, giving a dilution effect.
What is the most common haematological abnormality of pregnancy?
Iron deficiency anaemia - theres a 2-3 fold increase in iron requirements, mostly used by the baby.
What can iron deficiency during pregnancy cause?
Intrauterine growth restriction - when the baby is not as big as it should be.
What is the second most common haematological abnormality during pregnancy?
Vitamin B12 (folate) deficiency.
serum B12 decreases but liver levels stay the same.
Which clotting factors increase during pregnancy?
Clotting factors Vii, IX, X, fibrinogen.
Which anti-clotting factors decrease during pregnancy?
Protein S and C, anti-thrombin 3.
Fibrinolytic activity also decreases (clot busting).
How much does pregnancy increase thromboembolism risk?
6x.
DVT common - venous dilation and pressure on IVC.
Pulmonary embolism common.
What happens to the kidneys in pregnancy physiology?
Hydronephrosis (swelling), usually worse on the right.
What happens to urea and creatinine levels in pregnancy?
Filtration increases by 50% so their levels decrease.
What do the kidneys secrete more of in pregnancy?
creatinine urea protein vitamin D renin erythropoietin
What do the kidneys secrete less of in pregnancy?
Sodium
Water
