Physiological Changes During Pregnancy

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Physiological Changes During Pregnancy

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Physiological Changes During Pregnancy

  1. 1. PHYSIOLOGICAL CHANGESDURING PREGNANCYDr.Fadi AlfaqawiMedical OfficerUNRWA11th DEC 2012
  2. 2. OBJECTIVES:What! Where! Why!Pregnancy causes physiologicchanges nearly in all maternalorgan systems,Most return to normal afterdelivery.In general, the changes are moredramatic in multifetal than insingle pregnancies.Major adaptations in maternalanatomy, physiology, andmetabolism are required forsuccessful pregnancyTo distinguish normal physiologyfrom pathological diseasestates..
  3. 3. Hormonal Changes:
  4. 4. Hormonal changes:Progesterone synthesized by the corpus luteum until 35 post-conception days and by the placenta mainly thereafter, itdeceases smooth muscle excitability (uterus,gut,ureters) andrise body temp.Oestrogens (90%)oesteiol) increase breast and nipplegrowth, water retention and protein synthesis.TSH may be slightly low in the first trimester due to high hCGlevels. Increased total T4 is often seen. However, Freehormone remain normal. The thyroid is functioning normally ifthe TSH, Free T4 and Free T3 are all normal throughoutpregnancy.Pituitary secretion of prolactin rises throughout pregnancy.Maternal cortisol output is increased unbound level remainconstant.
  5. 5. Pancreas and FuelMetabolismDiabetogenic effects of pregnancy anti-insulin (CortisolProlactin Estrogen and Progesterone )Maternal response to feeding:-Hyperglycemia-Hyperinsulinemia-Hyperlipidemia-Resistance to insulin-Insulin resistance increases to 50-80% in third trimester-Borderline pancreas function leads to GDM.Fetal glucose levels are 20 mg/dl less than maternalvalues.
  6. 6. Genital Changes:Uterus:100g non-pregnant uterus weights1100g by term. Muscle hyperplasia occurs upto 20 weeks, with stretching after that .Cervix: may develop ectropion .Late inpregnancy cervical collagen reduces.Vagina: discharge increases due to cervicalectopy, cell desquamation increase productionon mucous from vasocongested vagina.
  7. 7. Haemodynamic changes:
  8. 8. Haemodynamic changes:BLOOD: From 10 weeks the plasma volume rises until32 weeks (50% > non-pregnant).Red cell volume rises increase by 18% if ironsupplementation not taken and by 30% if ironsupplementation is taken.Hence Hb falls due to dilution (Physiological Anemia).CV:{ COP= SVxHR } rises from 5 L/m to 6.5-7 L/m in thefirst 10 week.Peripheral resistance falls BP particularly diastolic fallsduring the 1st and 2nd trimesters by 10-20 mmHg.Venous distensiblity and raised venouspressure,Varicose veins.
  9. 9. Caval Compression:In supine position the gravid uterus compresses the IVCand decreases the CO without fall in the bloodpressure called as Concealed caval compression.Reasons for no fall in blood pressure are: Reflex vasoconstriction Diversion of blood through paravertebralvenous plexus.8 to 15% of pregnant women have Overt CavalCompression (supine hypotensive syndrome)Hypotension Sweating Bradycardia Pallor NauseaVomiting Prevention of SHS: (aim is to displace theuterus) Providing left lateral tilt 15 degrees Placingwedge under the right buttock
  10. 10. Overt Caval CompressionLeft Lateral Tilt
  11. 11. Respiratory system Changes:Tidal volume: + 40% (rises from 500mL to700mL)Breathing rate: + 10%Oxygen consumption: + 20%Breathlessness is common as maternal PaCO2 isset lower to allow the fetus to offload CO2.
  12. 12. Others: Gut motility is reduced, resulting in constipation,delayed gastric emptying, and with a lax cardiacsphincter, heartburn . Renal size increases by 1 cm in length. Frequency of micturation emerges early (GFRincreases by 60%) . Later from bladder pressureby the fetal head . Skin pigmentation : linea nigra, nipples, or aschloasma, palmar erythema , striae are common. Hair shedding from the head is reduced inpregnancy but increases in the puerperium .
  13. 13. Weight:On a Trimester Basis: First trimester: Most women put on around 1.6kgin the first three months. Second trimester: around 0.5kg a week for thenext three months (5.5 - 6.4kg) in total. Third trimester: and only around 5kg over thelast three months.But remember, these are average figures for large numbers ofwomen so just because your weight gain pattern is different, itdoesnt mean anything is wrong.
  14. 14. Weight.. Where do the pregnancy Kilosgo?Where do the pregnancy Kilos go?Maternal stores of nutrientsand muscle development3 KgIncreased body fluid 2 KgIncreased blood 1.5 - 2 KgBreast growth 600gEnlarged uterus 1 KgAmniotic fluid 1 KgPlacenta 600gBaby 3.4 - 4 KgTotal 11 - 16 Kg

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