Changes in physiological systems during pregnancy (1)
- 1. CHANGES IN PHYSIOLOGICAL SYSTEMS DURING PREGNANCY
- 2. 1. Blood • The blood volume increases by about 20% or about 1 L. • This increase is mainly because of increase in plasma volume. • It causes hemo dilution. • Because of great demand for iron by the fetus, the mother usually develops anemia
- 3. 2. Cardiovascular System Cardiac output • Generally, cardiac output increases by about 30% in the first trimester. After the 3rd month, cardiac output starts decreasing and reaches almost the normal level in the later stages of pregnancy. Blood pressure • Arterial blood pressure remains unchanged during the first trimester. During the second trimester, there is a slight decrease in blood pressure. It is due to the diversion of blood to uterine sinuses.
- 4. Pre-eclampsia • Pre-eclampsia is the hypertensive disorder of pregnancy. • It is otherwise known as toxemia of pregnancy. Cause for hypertension 1. Release of vasoconstrictor substances from placenta 2. Hypersecretion of adrenal hormones and other hormones, which cause vasoconstriction
- 5. Eclampsia • Eclampsia is the serious condition of pre- ecclampsia characterized by severe vascular spasm, dangerous hypertension and convulsive muscular contractions almost like seizures. • It occurs just before, during or immediately after delivery. It leads to death, if timely treatment is not given.
- 6. • Features of eclampsia 1. Spasm of blood vessels 2. Very severe hypertension 3. Renal failure 4. Liver failure 5. Heart failure 6. Convulsions 7. Coma.
- 7. 3. Respiratory System • Overall activity of respiratory system increases slightly. Tidal volume, pulmonary ventilation and oxygen utilization are increased.
- 8. 4. Excretory System • Renal blood flow and GFR increase resulting in increase in urine formation. • It is because of increase in fluid intake and the increased excretory products from fetus.
- 9. 5. Digestive System • During the initial stages of pregnancy, the morning sickness occurs in mother. • It involves nausea, vomiting and giddiness. This is because of the hormonal imbalance. • The motility of GI tract decreases by progesterone and constipation is common. • Indigestion and hypochlorhydria (decrease in the amount of hydrochloric acid in gastric juice) also occur.
- 10. 6. Endocrine System i. Anterior pituitary During pregnancy, the size of anterior pituitary increases by about 50%. And secretion of corticotropin, hyrotropin and prolactin increases. However, the secretion of FSH and LH decreases very much.
- 11. ii. Adrenal cortex There is moderate increase in secretion of cortisol, which helps in the mobilization of amino acids from the mother’s tissues to the fetus. iii. Thyroid gland The size and the secretory activity of thyroid gland increase during pregnancy. The increased secretion of thyroxine helps in the preparation of mammary glands for lactation.
- 12. v. Parathyroid glands Parathyroid glands also show an increase in the size and secretory activity. Parathormone is responsible for maintenance of calcium level in mother’s blood in spite of loss of large amount of calcium to fetus.
- 13. 7. Nervous System • There is general excitement of nervous system during pregnancy. • It leads to the psychological imbalance such as change in the moods, excitement or depression in the early stages of pregnancy.