Effect of Pregnancy on Maternal Physiology Flashcards
How much weight do mothers gain on average during pregnancy?
- 5 kg
- 6kg - uterus, foetus, breast
- 3 kg fat reserves for lactation
- Remainder is fluid
How can pregnancy cause varicose veins?
Pressure on IVC can impede venous return from lower limbs and may impair function of valves (combined with relaxation of vessels and valves via hormonal effects)
Why do pregnant women often need to urinate more often?
Weight of foetus on bladder
What hormone causes softening of ligaments?
Relaxin
What problems can relaxin cause?
- Sacroiliac and pubic symphysis pain due to relaxig of ligaments -> increased movement of joints
- Pregnancy related pelvic girdle pain (PGP)
What can happen to the abdomen during pregnancy?
- Diastasis recti (rectus abdominis splits and does not join back together)
- Striae gravidarum (stretch marks)
What changes can happen to the skin in pregnancy?
- Linea negra
- Melasma
- Increased estrogen (palmer erythema, spider naevi)
What cardiovascular adaptations happen during pregnancy?
- Blood volume increase
- Blood composition
- TPR decrease
- CO increase
- Blood pressure
What happens to the plasma volume in pregnancy?
Increases 50%
What happens to haemotopoiesis in pregnancy?
Increased by up to 30% but increase in plasma volume means that red cell count, haematocrit and haemoglobin concentration are all reduced (physiological anaemia)
What circulatory adaptations in blood volume and composition happen?
- Small increase in WBC
- Increased platelet production, but increased destruction so no overall change in count
- Increased clotting factors present thromboembolism risk
How can pregnancy cause heat intolerance?
Pregnancy hormones can reduce sensitivity to pressor agents such as angiotensin, hence peripheral vasodilation (reduce TPR)
How can estrogen cause vasodilation?
Increases vascular endothelial growth factor (VEGF) and nitric oxide (NO) production in endothelial cells
- Endothelial cells release (prostaglandin I2 or PGI2)
How can pregnancy cause an ejection systolic murmur?
Reduced TPR triggers the RAAS system increasing blood volume
How much does CO increase in in weeks 6-28?
30-50%
- HR increase from 70 to 80-80/min
- SV by ~10%
When does CO return to normal?
6 weeks post-partum
How can CO be effected by posture?
CO can fall because of IVC obstruction by uterus resulting in hypotension/fainting when lying flat (reduced venous return)
What happens to the BP in the second trimester?
Usually falls
- Systolic: 5-10 mmHg
- Diastolic: 10-15 mmHg
(before birth rises to pre-pregnancy levels)
What is pre-eclampsia?
- Placental problem involving an increase in BP, proteinuria, epigastric pain, brisk reflexes, head ache and oedema,
- May involve failure of second wave of trophoblasts to invade wich normally impair the capacity of material spiral arterioles to constrict (12-16 wks)
How common is pre-eclampsia?
8% of pregnancies
What are the risk factors for pre-eclampsia?
- Previous pregnancy with pre-eclampsia
- > 40
- Family histry
- Obesity
- Primigravida
What can increased vsscular resistance in the placenta cause|?
- Decreased blood to placenta
- Hypertension in mother
- Renal arteriolar damage causes oedema, glomerular damage and proteinuria (acute atherosis)
What is the treatment for pre-eclampsia?
- Only cure is delivery
- Antihypertensives
- Monitor
What is eclampsia?
- Seizures, coma, increased intracranial pressure
- Significant risk of cerebral haemorrhage
- Extreme hypertension (eg 180/120)
What is the maternal mortality rate of eclampsia?
8-36%
What interventions can be done to treat eclampsia?
- Magnesium sulphate (vasodilator)
- Antihypertensives
- Rapid delivery
- Careful fluid balance
How is the respiratory system effected by pregnancy?
- Progesterone increases sensitivity of central CO2 receptors
- More ventilation
- Increase tidal volume ~ 40%
- Ventilation rate unchanged
How is the renal system affected by pregnancy?
- Increased urea (from foetus), increased renal function
- Increased GFR as a result of increased CO
- Decreased plamsa, urea, creatinine and uric acid
What is the most useful renal marker during pregnancy?
Uric acid as it rises before creatinine in response to renal impairment (e.g. pre-eclampsia)
How can ureters be affected by pregnancy?
Can be dilated which can predispose to infection
When is morning sickness most frequent?
first 12-14 weeks
What is thought to be the cause of morning sickness?
HCG levels increase (can be due to twins or hyaditiform mole)
What is thought to be the cause of constipation during pregnancy?
- Pressure of uretus on rectum and lower colon
- Decreased motility, progesterone effect on smooth muscle
What is GAstric acid reflux thought to be due to during pregnancy?
- Relaxation of lower esophageal sphincter
- Relaxation of GI SM (progesterone)
- Pressure of uretus
- Worse lying down
- Aspiration risk during endotracheal intubation
How much does daily calorific requirment increase by during pregnancy?
~ 15% (200-300 kcal)
How much fat is laid down in 1st trimester to provide energy for later when growth of foetus is very rapid?
~ 3 kg
What stages of pregnancy are maternal tissues more sensitive to insulin?
Early stages (increased protein synthesis)
When does the growth rate of foetus peak?
30 - 36 weeks
What happens metabolically later in pregnancy?
- Relative insulin resistance predisposing to ‘high-normal’ glucose levels
- Increased lipolysis supplying mother with source of energy
- Increase in circulating triglycerides stored in mammary tissues
- Increased requirement for protein
What are the risk factors for gestational diabetes?
- Race (black)
- Obesity
- FH
What is gestational diabetes a precursor for?
Can be a precursor for actual type 2 diabetes
What is gestational diabetes associated with?
Foetal macrosomia (increased inulin resistance, high glucose) complications
What are the vitamin and mineral requirments for pregnant women?
Vitamins
- Folic acid for neural tube fusion (pre-conception)
- Vegetarians may need to increase B12 intake
- High levels of vit A may lead to foetal abnormalities
- Vit D supplementation is recommended
Minerals - Calcium: Maternal gut absorption increases Active transport across lacenta Increase in release from maternal bone
Zinc + Iron
What does zinc help with in pregnancy ?
- Important in many metabolic processes
- Protein synthesis
- Nucleic acid synthesis
- Synthesis/activity of insulin
- Increased dietary need, especially vegans
What are the functions of iron in pregnancy?
- Globally, high incodence of maternal iron deficiency
- If dietary iron low, may need supplements
- Supplementation with normal iron stores is undesirable, may increase oxidative stress
What are some secretions from the placenta in pregnancy?
- hCG has a key role in maintaining pregnancy
- Other placental proteins and steroid s
What are some endocrine secretions from the mother during pregnancy?
- Increased growth hormone releae
- Decreased FSH and LH
- Increased prolactin
- Increased parathyroid hormine
- Pituitary increases in size (production of prolactin adn ACTH and oxytocin)
- Thyroid increases in size die to hCG (similar in structre to TSH)
After how long does the uterus go back to normal?
6 weeks `
What can lead to Amenorrhea and what can be associated with it?
- Duration related to frequency of duration and suckling
- May be associated with hot flushes and vaginal dryness
What can take longer than 6 weeks to restore to normal after pregnancy?
Coagulation system
What normalises extremely rapidly after pregnancy?
Glucose tolerance
What is Amenorrhea?
Absence of menstruation
