Physiological changes in pregnancy

1. Physiological changes in pregnancy Dr.Areefa Al Bahri

2. The major maternal physiological adaptation to pregnancy 1-Systemic changes: -Blood volume homeostasis. -cardio vascular system. 2-Respiratory changes. 3-urinary tract and renal function.. 4-Reproductive organs. 6-endocrine changes.

3. systemic changes • volume homeostasis: • fluid retention is the most fundamental systemic changes of normal pregnancy. • the total blood volume is increased during pregnancy by 30%. • the most marked expansion occurs in extra cellular volume (ECV) with some increase in intra cellular water.

4. Changes in the cardiovascular system • These complex changes are necessary to: • meet evolving maternal changes in physiological function • to promote the growth and development of the uteroplacental-fetal unit • to compensate for blood loss at the end of labour. • The key physiological changes that occur are

5. The key physiological changes that occur cardiac system

6. Blood changes: The marked increase in plasma volume associated with normal pregnancy causes dilution of many circulating factors. Hematological changes Decrease in: • red cell count. • hemoglobin concentration. • haematocrit. • Platelets

7. Increase in : • Plasma volume • Red cell mass • Total blood volume • white cell count. • erythrocyte segmentation rate . • fibrogen concentration (cloating factor). • Plasma.

8. normal changes in heart sounds during pregnancy: • increase loudness of both S1 & S2. • >95% develop systolic murmur which disappears after delivery. • 20% have a transient diastolic murmur. • 10% develop continues murmur due to increase mammary blood flow. • Relative tachycardia • collapsing pulse

9. Pregnancy problem due these changes • Physiological edema • Renin and aldosterone activity are increased by oestrogens, progesterone and prostaglandins, leading to increased fluid and electrolyte retention. • Physiological anemia • The total plasma volume is increase in higher percentage in comparison to RBC which result in hemodilution

10. Decrease blood pressure • Increase cardiac output is this lead to decrease arterial blood pressure by 10%, therefore resistance to flow must be decreased. In addition this can be result in decrease in systemic vascular resistance, particularly in the peripheral vessels. The decrease begins at 5 weeks' gestation, reaches a nadir in the second trimester (a 21% reduction) and then gradually rises as term approaches

11. supine hypotensive syndrome • The enlarging uterus compresses both the inferior vena cava and the lower aorta when the woman lies in supine position. This reduces venous return to the heart this condition happen in 10% of pregnant women. • Sign of supine hypotension • hypotension, bradycardia, dizziness, light-headedness.

12. Respiratory changes • Pregnancy is associated with marked changes in respiratory physiology mediated by biochemical and mechanical factors. These accommodate the progressive increase in oxygen consumption and the physical impact of the enlarging uterus. Normal oxygen consumption is 250mL/min at rest and increases by 20% in pregnancy in order to meet the 15% increase in the maternal metabolic rate

13. Changes in pregnancy result in an overcompensation to this respiratory demand. The resulting hyperventilation causes the arterial oxygen tension to increase and arterial carbon dioxide tension to fall, accompanied by a compensatory fall in serum bicarbonate. A mild respiratory alkalosis is therefore normal in pregnancy (Table 14.6).

14. Hyperventilation can be extremely uncomfortable and may lead to dyspnoea and dizziness. Although it is not usually associated with pathological processes, care must be taken not to dismiss it lightly and miss a warning sign of cardiac or pulmonary disease (Steinfeld & Wax 2001) (Box 14.2).

15. The shape of the chest changes as diameters increase, by about 2cm, resulting in a 5–7cm expansion of the chest circumference.’ • The flaring of the lower ribs, causes the diaphragm to rise by up to 4cm, its contribution to the respiratory effort increasing with no evidence of being impeded by the uterus. • These changes are thought to be mediated by the effect of progesterone, which together with relaxin, increases ribcage elasticity by relaxing ligaments. Progesterone also mediates

17. Respiratory changes • increaseO2 demand by 20 %. • ↑tidal volume with normal respiratory rate. • ↑po2 and ↓pco2 withcompensatory ↓HCO3(mild compensated respiratory alkalosis). • Breathlessness due to hyperventilation and elevation of diaphragm. • tissue and oxygen availability to placenta improves.

18. ventilatory changes: • thoracic anatomy changes. • tidal volume increases. • vital capacity increase. • functional residual capacity decrease.

19. Central nervous system • The pituitary gland increases in size by 30–50% in pregnancy accounting for much of the increased pituitary activity. • Oestrogen and progesterone readily enter the brain acting on a multitude of nerve cells changing the balance between inhibition and stimulation.

20. Central nervous system • Oxytocin neurons are inhibited from releasing the stored oxytocin prematurely through several hormonal mechanisms involving progesterone, oestrogen and opioid peptides. At term, progesterone secretion falls and the inhibitory mechanism modified to allow gradual release of oxytocin in labour followed by a surge at the time of birth.

21. Sleep disturbances are a common complaint of pregnancy. Various hormonal and mechanical influences promote insomnia leading to disturbed sleep during pregnancy in most women (Santiago et al 2001).’ • This worsens toward the end of pregnancy and continues to some extent for 3 months postpartum (Hedman et al 2002).

22. Interventions include establishing sleep – wake habits, avoiding caffeine, relaxation techniques, massage, heat and support for lower back pain, modifying sleep environment, limiting fluids in the evening and avoiding passive smoking. Sleep medications should be avoided. Some studies have shown that sleep loss in the last few weeks of pregnancy are associated with increased labour length and LSCS rates (Lee & Gay 2004).

23. Pregnant women's sleep patterns are affected by both mechanical and hormonal influences. These include nocturia, dyspnoea, nasal congestion, stress and anxiety as well as muscular aches and pains, leg cramps and fetal activity (Box 14.3).

24. The urinary tract and renal function • blood flow increase (60-70%). • glomerular filtration increased (50%). • clearance of most substances is enhanced. • plasma creatinine ,urea,urate are reduced. • glycoseuria is normal.

25. Alimentary system changes • the gums becomes spongy. • the lower oesophageal sphincter is relaxed (hurt burn). • gastric secretion is reduced. • the intestinal musculature is relaxed (constipation).

26. Reproductive organs • the uterus: • the adult uterus comprising three layers: • inner layer thin circular MF. • outer layer thin long MF. • central layer thick inter locking fiber. • the ratio of muscle to connective tissue increase from the lower part of the uterus to the fundus.

27. in early pregnancy uterine growth result from both hyperplasia and hypertrophy while later hypertrophy accounts for most of increase. • it weight one kilo gram at term( in pre pregnancy 50-60 grams • as the pregnancy advanced the uterus divided into upper and lower uterine segment the lower uterine segment composed of lower part of uterus and the upper cervix composed mainly from connective tissue because of this the lower uterine segment becomes stretched in late pregnancy.

28. the cervix: • the cervix becomes softer and swollen in pregnancy • the mucus gland becomes distended and secrete mucus which forms a mucus plug that is expelled in labour as the show. • prostaglandins and collagenase especially in last weeks of pregnancy act on collagen fiber make cervix more softer.

29. the vagina : • the vaginal mucosa becomes thicker during pregnancy. • the vaginal discharge during pregnancy increased due to increase desquamation of the superficial vaginal mucosal cells

30. D-breasts and lactation : • the earliest changes is a swelling of the breast tissue. • oestrogen leads to increase in number of glandular ducts. • progesterone leads to proliferation of glandular epithelium of the alveoli. • prolactine leads to active secretion of milk after birth.

31. Endocrine changes: • prolactine concentration increases markedly but act after delivery. • insulin resistance develop. • thyroid function changes little. • trans placental calcium transport is enhanced. • corticosteroid concentration increased. • aldesterone concentration increased. • angiotensin and renine increased

32. Hormones produced within uterus • human chorionic gonadotrophin (HCG): • it is secreted by trophoblast and can be detected in serum 10 days after conception (RIA). • there is high level of circulating HCG in early pregnancy (to provide a suitable environment for implantation and development). • to support corpus luteum secretion of oestrogen and progesterone in the first trimester until the placenta becomes able to produce these hormone. • the peak level normally occur in the 12th week .

33. constant level of HCG in late pregnancy is useful in: • controlling placental secretion of Estrogen progesterone. • suppressing maternal immune system against fetus. • the human chorionic gonadotrophine normally disappear from urine 7-10 days after delivery of placenta.

34. Alimentary system changes • the gums becomes spongy. • the lower oesophageal sphincter is relaxed (hurt burn). • gastric secretion is reduced. • the intestinal musculature is relaxed (constipation).

35. Reproductive organs • the uterus: • the adult uterus comprising three layers: • inner layer thin circular • outer layer thin long • central layer thick inter locking fiber. the ratio of muscle to connective tissue increase from the lower part of the uterus to the fundus.

36. in early pregnancy uterine growth result from both hyperplasia and hypertrophy while later hypertrophy accounts for most of increase. • it weight 1 kg at term( in pre pregnancy 50-60 grams) • as the pregnancy advanced the uterus divided into upper and lower uterine segment the lower uterine segment composed of lower part of uterus and the upper cervix composed mainly from connective tissue because of this the lower uterine segment becomes stretched in late pregnancy.

37. the cervix: • the cervix becomes softer and swollen in pregnancy with the result columnar epithelium lining cervical canal becomes exposed to vaginal secretion. • oestradiol stimulate growth of columnar epithelial of the cervical canal so it becomes violate in color • the mucus gland becomes distended and secrete mucus which forms a mucus plug that is expelled in labour as the show. • prostaglandins and collagenase especially in last weeks of pregnancy act on collagen fiber make cervix more softer.

38. the vagina : • the vaginal mucosa becomes thicker during pregnancy. • the vaginal discharge during pregnancy increased due to increase desquamation of the superficial vaginal mucosal cells and action of pregnancy hormones

39. D-breasts and lactation : • the earliest changes is a swelling of the breast tissue. • oestrogen leads to increase in number of glandular ducts. • prolactine leads to active secretion of milk after birth.

40. Endocrine changes: • prolactine concentration increases markedly but act after delivery. • human growth hormone is suppressed . • insulin resistance develop. • thyroid function changes little. • trans placental calcium transport is enhanced. • corticosteroid concentration increased. • aldesterone concentration increased. • angiotensin and renine increased

41. Hormones produced within uterus human chorionic gonadotrophin (HCG): • it is secreted by trophoblast and can be detected in serum 10 days after conception (RIA). • there is high level of circulating HCG in early pregnancy (to provide a suitable environment for implantation and development). • to support corpus luteum secretion of oestrogen and progesterone in the first trimester until the placenta becomes able to produce these hormone. • the peak level normally occur in the 12th week .

42. constant level of HCG in late pregnancy is useful in: • controlling placental secretion of Estrogen progesterone. • suppressing maternal immune system against fetus. • the human chorionic gonadotrophine normally disappear from urine 7-10 days after delivery of placenta.

43. human placental lactogen • it is secreted by syncytotrophoblast. • It is level increase when the level of HCG start to drop . • HPL has no effect on fetus. • HPL effect on : 1-the breast: • mammary growth during pregnancy. • produce of colostrums. • milk production lactation.

44. 2-protiens: • HPL stimulate protein synthesis at cellular level. 3-carbohydrate: • stimulate insulin secretion . • inhibit insulin action. 4-fat: HPL mobilize fat from body store (lypolysis) lead to increase maternal blood glucose and maternal tissue can not utilize the glucose so the glucose will be available for fetus.

45. Estrogen • it is produce by corpus luteum in early pregnancy. • it is produce by placenta in late pregnancy. • fetus (liver and adrenal ) provide certain enzyme which are lack in placenta. role of estrogen: • On connective tissue: estrogen leads to polymerization of mucopoly saccarides of the ground substance leads to loose connective tissue mainly in the cervix. • On the protein: estrogen stimulate directly RNA synthesis lead to protein synthesis.

46. progesterone • it is production same as estrogen. • it has effect on smooth muscle leads to decrease muscle excitability leads to muscle relaxation mainly in uterus.

47. Thyroid function • increase thyroid binding globulin. • increase bound form of T3,T4. • no change in free form of T3,T4. So no evidence to support what previously thought to be physiological such as increase in size of thyroid gland , increase BMR, body temperature, heart rate.

48. Diagnosis of pregnancy • History: symptoms. • Examination: signs. • Investigation : pregnancy test and ultrasound.

49. symptoms of pregnancy 1-Amenorrhoea: abrupt cessation of menses in a woman with regular cycle is highly suggestive. 2-breast symptoms: tenderness and fullness may be noticed . 3-frequency of micturation : pressure on the urinary bladder by enlarging uterus.

50. 4-nausea with or without (morning sickness). 5-abdominal enlargement. 6-fetal movement: • quickening is the first feels fetal movement PG at (18-20wks). • Multi para at (16-18wks).