Physiological Adaptations In Pregnancy Flashcards
What are the hormones in early pregnancy
- Corpus luetum supports early pregnancy by progesterone. oestrogen ad inhibin
- Function declines from week 10 by end of first trimester placenta takes over.
- Oestrogen and Progesterone- noncontractile uterus and fosters development of an endometrium conductive to pregnancy
- Inhibin downregulates FSH (stops further pregnancies)
Describe the role of hormones in pregnancy
Progesterone- increased (syncytiotrophoblasts )
• Relaxes smooth muscle ie lower oesophageal sphincter -reflux
• Slows gastric emptying
• Dilation of vessels
Oestrogen- increased (Trophoblasts)
• leads to breast tissue growth, water retention, protein synthesis
Relaxin: Produced by villous cytotrophoblast
• Softens the cervix and pelvic ligaments in preparation for childbirth
Describe hcg and tsh relation
TSH- lower in first trimester due to high HCG (similar structure) Increased T4 can be seen. HCG can also stimulate the TSH receptor and cause thyroid hormone productive. HCG peaks at around 12-13 weeks, increases levels associated with HG
Prolactin levels increase
• Stimulates breast development and promotes and maintain lactation postpartum.
What is the role ofproleatin and oxytocin
Prolactin (and oxytocin and Progesterone) levels increase
Stimulates breast development and promotes and maintain lactation postpartum. Oxytocin
• Major role in labour - uterine contraction, dilate cervix
• Let down process of breast feeding
Why do changes to cvs occur
During pregnancy, oxygen consumption increases.
• Fetus has its own increasing oxygen requirements
• Increasing size of the uterus and increasing maternal metabolic rate.
• Physiological changes in the maternal cardiovascular system occur in order to increase delivery of oxygenated blood to the tissues.
What are the changes o cvs
• ↑ plasma volume (50%) – increased preload
• ↑ stroke volume
• lower systemic vascular resistance – decreased afterload
• ↑ heart rate by approximately 10-20 bpm (18%)
• overall ↑ cardiac output by 30–50%; half of the total increase occurs by 8 weeks of
gestation, max at 16 weeks and peripartum. CO=SVxHR
• CO Peaks at 16 weeks, and during labour and postpartum.
What times throughout gestation are women with pre-existing heart disease at most risk
Aortic stenosis, if severe they do not cope well with hypotension and tachycardia
Adequate preloadis required in the ventricle to generate enough pressure across the valve
Avoid veno calm compression ,blood loss
Why s there slight displacement of apex beat
Mild hypertrophy and rotation of cardiac axis
What are he scm changes
• atrial and ventricular ectopics
• left shift in the QRS axis
• small Q wave and inverted T wave in lead III
• ST segment depression and T waveinversion in the inferior and lateral
lead.
May be due to physiological changes
What are the renal chanegs
• ↑ Glycosuria
• ↑Bicarbonaturia
• ↑Calciuria
• ↑Protienuria
• ↓Plasma Osmolarity - peripheral oedema
ENDOCRINE- ↑Renin ↑Erythropietin ↑Active vit D
Baby’s head sittong on bladder. Element of urinary stasis - high risk of urinary infection.. slight hydronephross and frequent urination are common. Need to krealise when physiology becomes pathology though
What are teh changes to calcium
• Intestinal calcium absorption doubles during pregnancy, driven by 1,25- dihydroxyvitamin D (calcitriol) and other factors, and this appears to be the main adaptation through which women meet the calcium demands of pregnancy
What are the changes to gI tract
See slide
Decsribe immunity chanegs
- Th1 → Th2 immunity
- In order to prevent rejection of the fetus, there is a reduction in cell- mediated immunity and T helper (Th)1 cytokine production during pregnancy. This is balanced by an increase in humoral immunity and Th2 cytokine production. • hCG reduces maternal levels of IgA, lgG and 1gM.
- The immunosuppression of pregnancy- greater risk of infection
- Can improve some medical disorders is psoarisis (th1 mediated)
- Can worsen others ie eczema (th2 mediated)
What are the changes to respiratory physiology
— ↑oxygen consumption (20%) secondary to an ↑ in resting metabolic rate
— Progesterone stimulants respiration and respiratory drive. ↑ in alveolar ventilation
— 40% ↑ in resting minute ventilation (MV) secondary to an ↑ in tidal volume (TV) with a stable respiratory rate (RR); MV= RRxTV
— Maternal hyperventilation leads to an ↑ in arterial pO2, →in arterial pCO2, a compensatory fall in bicarbonate (18–22 mmol/L) and mild respiratory alkalosis.
— Normal pH in pregnancy ranges between 7.40–7.45
What are the changes o PEFR, FEV1, FRC, VC
- PEFR (peak expiratory flow rate) and FEV1 (forced expiratory volume in 1s) unchanged in pregnancy
- FRC: 20% decrease in third trimester due to a decrease in residual volume and exp reserve plume
- Vital capacity and total lung capacity: minor nonsignificant decreas (due to baby taking up space)