Physiological Affect of Pregnancy Flashcards
Where can the fundus of the uterus be found at 12, 20 and 36 weeks gestation?
Uterus becomes palpable at 12 weeks
Reaches level of the umbilicus at 20 weeks
Reaches level of the xiphi-sternum at 36 weeks
How does the SFH correspond to weeks gestation?
SFH should be the number of weeks gestation they are
• +2cm from 20-36 weeks
• +3cm between 36-39 weeks
• +4cm at 40 weeks
Describe the cardiovascular changes associated with pregnancy
Cardiac output increases by 50%
HR increases by 15bpm
BP reduced between 12-26 weeks due to increased progesterone relaxing smooth muscle. BP returns to pre pregnancy value around 36 weeks
Ejection systolic murmur found in 90% of pregnant mothers
Describe the hematological changes associated with pregnancy
Blood volume increased by 40-50% whilst red cell mass only 25% hence anaemia
Increased white cells especially during labour
Platelets decrease slightly
Clotting factors – mostly all increase in number (especially fibrinogen) hypercoagulable
Describe common endocrine changes during pregnancy
Progesterone – increases throughout pregnancy, synthesised by the corpus luteum and then the placenta. Prevents preterm labour
Oestrogen – causes breast and nipple growth, promotes uterine blood flow, myometrial growth and cervical softening, increases oxytocin sensitivity and increases water retention.
Human placental lactogen – similar to growth hormone and modifies maternal metabolism. It increases insulin production but decreases its peripheral effect (this liberates fatty acids and spares glucose for the foetus).
Anterior Pituitary gland – generally enlarges increasing prolactin, and cortisone
Posterior pituitary – produces oxytocin during first stage of labour and during suckling
Thyroid – increased due to increased demand of pregnancy. Relative iodine insufficiency due to increased renal clearing so thyroid triples its uptake of iodine from the blood. TBG increases by end of first trimester. So, at first T3 and T4 increasses then drops back to normal levels
How does the respiratory system change through pregnancy?
Movement of diaphragm upwards
Increased tidal volume due to progesterone
Respiratory rate increases slightly
How does the genital tract change through pregnancy
Uterus – muscle hypertrophy and greatly increased blood supply
Cervix – reduced collagen, hypertrophy of glands and increased discharge
Vagina – increased blood supply and lowered pH to keep it bacteria free
How does the urological system change through pregnancy
Increased size
Increased renal blood flow
Increased GFR
When are VTE most likely to occur in a pregnant woman?
VTE most commonly occurs post-nataly, so there should be a high level of suspicion.
What is the normal physiology of the reproductive tract and cardiac output post-partum
Uterus – undergoes rapid involution, by 2 weeks it is back in the pelvis and not palpable
Vagina – wall initially swollen but rapidly regains tone
Cervix – remains dilates by 3-6cm at 4-6 days but after 2 weeks is less than 1cm
Cardiac output – initially increased due to return of blood from contracted uterus. Plasma volume rapidly decreases via diuresis
How does pregnancy affect Rheumatoid Arthritis
RA often gets better but exacerbations commonly occur in the puerperium
Avoid Methotrexate use – try sulfasalazine instead but give extra folate
Avoid NSAIDs in 3rd trimester – early closure of DA and renal impairment
How does pregnancy affect Systemic Lupus Erythematous
Exacerbations are much more common
Prone to PET if renal impairment
Still birth and miscarriage common
Should be on 75mg aspirin
Control disease with azathioprine and hydroxychloroquine 6 months prior to conception
