Physiological Changes During Pregnancy Flashcards
What hormones are present in early pregnancy?
- Corpus luetum supports early pregnancy by producing oestrogen, progesterone and inhibin.
- Function declines from week 10 by end of first trimester placenta takes over.
- Oestrogen and Progesterone - noncontractile uterus and fosters developmetn of an endometruum conductive to pregnancy.
- Inhibin downregulates FSH to stop further pregnancies.
What does progesterone do in pregnancy?
- Relax smooth muscle ie lower oesophageal sphincter
- Slows gastric emptying
- Dialation of vessels
What does oestrogen do during pregnancy?
Increased (trophoblasts)
- Leads to breast tissue growth, water retention and protein synthesis
What does relaxin do during pregnancy?
It is produced by the villous cytotrophoblast.
- Softens the cervix andpelvic ligaments in preparation for childbirth
How do TSH and hCG change during pregnancy?
TSH - lower in first trimester due to high hCG (similar structure). Increases T4 can be seen. HCG can also stimulate the TSH receptor and cause thyroid hormone productive.
hCG peaks at around 12-13 weeks, increases level associated with hCG.
How do prolactin levels change?
Prolactin levels increase
- Stimulates breast development and promotes and maintain lactation postpartum.
What does oxytocin do?
- Major role in labour
- Let down process of breast feeding.
How and why does oxygen consumption change during pregnancy?
Oxygen consumption increases.
- Foetus has its own increasing oxygen requirements
- Increasing size of the uterus and increasing maternall metabolic rate
- Physiological changes in the maternal cardiovascular system occur in order to increase delivery of oxygenated blood to the tissues.
What cardiovascular changes occur to accommodate for the increased oxygen requirements?
- Increase plasma volume (50%) - increased preload
- Increase stroke volume
- Decrease systemic vascular resistance - decreased afterload
- Increase heart rate by approximately 10-20bpm
- Increase cardiac output by 30-50%; half of the total increase occurs by 8 weeks of gestation, max at 16 weeks peripartum
- CO peaks at 16 weeks and during labour and postpartum.
How does the heart change during pregnancy?
- Displacement of apex beat during pregnancy
- Lower blood pressure - Progesterone dilates vessels
- Heart rate increases by about 20bpm to increase cardiac output
- Mild hypertrophy
What physiological changes can occur to an ECG in pregnancy?
- Atrial and ventricular actopics
- Left shift in QRS axis
- Small Q wave and inverted T wave in lead III
- ST segment depression and T wave inversion in the inferiror and lateral leads
How does your blood pressure change throughout pregnancy?
Normal at start and end but a drop between 17-32 weeks.
Important to monitor and ensure it doesn’t go up by too much (higher than it started)
What renal changes occur during pregnancy?
- Increase glycosurea
- Increase bicarbonaturea
- Increase calciurea
- Increase proteinurea
- Decrease plasma osmolarity.
- Also: Increase renin, EPO, active VitD
Why are you at a high risk of urine infections during pregnancy?
As smooth muscle relaxes so less contractions occur so the bladder doesnt empty properly.
Also, your bladdergets compressed by the uterus so it prevents proper emptying.
How does calcium change during pregnancy>?
Intestinal absorption doubles during pregnancy driven by 1,25-dihydroxyvitamin D (calcitriol) and other factors.
This appears to be the main adaptation through which women meet the increased calcium demands of pregnancy.
What GI changes occur during pregnancy?
- Constipation and bloating - caused by relaxation of smooth muscle and decreased peristalsis.
- Acid Reflux and Heartburn - caused by relaxation of lower oesophageal sphincter
- Nausea (morning sickness)
- Pica
How does immunity change during pregnancy?
- Reduction in cell-mediated immunity and T helper cytokine production during pregnancy. This is balanced by an increase in humoral immunity and Th2 cytokine production.
- hCG reduces maternal. levels of IgA, IgG and 2gM.
- The immunisuppression of pregnancy - greater risk of infection.
These changes in immunity mean that Th1 mediated disorder (e.g. psoriasis) mporve during pregnancy but Th2 disorders (e.g. eczema) can worsen.
How does your respiratory physiology change during pregnancy?
- Increase oxygen consumption secondary to increase metabolic rate.
- Progesterone stimulates respiration and respiratory drive. This results in an increase in alveolar ventilation.
- 40% increase in resting minute ventilation (MV) secondary to an increase in tidal volume (TV) with a stable respiratory rate (RR) MV = RRxTV
How are blood gases different in pregnant people?
- High arterial pO2,
- Fall in arterial pCO2,
- A compensatory fall in bicarbonate (18-22),
- Mild respiratory alkalosis.
- Normal pH in pregnancy ranges between 7.4-7.45
What parts of respiratory physiology stay they same in pregnancy?
- PEFR (peak expiratory flow rate)
- FEV1 (forced expiratory volume in one second)
What anatomical changes occur in respiratory physiology?
Early: increase in subcostal angle, transverse diameter and circumference of the chest.
Later: elevation of the diaphragm by the gravid uterus up to 4cm
How does MSK change in pregnancy?
- Symphysis pubis discomfort
- Waddling gait
- Progesterone and relaxin loosen the sacroilliac joint and pubic symphysis which cause pain in the ribs and coccygeal (tail) bone.
How is glucose in normal pregnancy?
- Insulin resistance is increased in pregnancy. This usually starts mid-pregnancy and progressively increases in the third trimester.
- This means that there is an increase in maternal blood glucose levels.
- This occurs because of human placental lactogen (hpl)
- Hyperplasia od pancreatic beta cells, insulin levels increase in pregnancy and counteract the effect of increasing insulin resistance.
What is gestational diabetes (GDM)?
- Diabetes first diagnosed in pregnancy
- 3-6% of the pregnant population, and is on the rise due to increasing obeisity and maternal age.
- It is associated with adverse outcomes in the mother, foetus and neonate,
- Strict glycaemic control improves both maternal and foetal outcomes
- Diagnosed with a glucose tolerance test at 28 weeks - fasting over 5.6mg then 75g of sugar and after 2 hours stillover 7.8mg.
