This review highlights the significant physiological changes that occur during normal pregnancy, which are essential for nurturing the developing fetus and preparing the mother for labor and delivery. These changes include: 1. **Haematological Changes**: Plasma volume increases by 50% by 34 weeks, leading to a fall in hemoglobin concentration, hematocrit, and red blood cell count. Platelet count may decrease in some women, but remains within normal limits. Iron, folate, and vitamin B12 requirements increase significantly. 2. **Cardiac Changes**: Cardiac output increases by 20-40%, with a peak at 20-28 weeks. This is achieved through an increase in stroke volume and heart rate. Blood pressure decreases in the first and second trimesters but returns to non-pregnant levels by term. Positional changes can affect cardiac output, with supine position reducing it by 25%. 3. **Renal Changes**: Systemic vascular resistance (SVR) decreases by 40%, leading to arterial under-filling. Renal blood flow and glomerular filtration rate (GFR) increase by 40-65% and 50-85%, respectively. Renal size increases by 1-1.5 cm, and hydronephrosis is common. 4. **Respiratory Changes**: Oxygen demand increases by 15%, leading to a 40-50% increase in minute ventilation. This results in a mild respiratory alkalosis. 5. **Alimentary Tract Changes**: Nausea and vomiting are common, possibly to prevent consumption of teratogenic substances. Mechanical changes in the gastrointestinal tract due to the growing uterus can lead to symptoms like reflux. 6. **Endocrine Changes**: Thyroid function and adrenal gland activity are altered, with increased production of thyroxine-binding globulin and mineralocorticoids. Pituitary gland enlargement is observed, with increased prolactin and oxytocin levels. 7. **Metabolic Changes**: Glucose metabolism adapts to shunt glucose to the fetus, leading to insulin resistance and hyperglycemia. Lipid and protein metabolism also change to meet the needs of the developing fetus. 8. **Calcium Metabolism**: Increased dietary absorption of calcium is necessary to meet fetal needs, leading to hypercalciuria and a risk of kidney stones. These changes are crucial for the health and development of both the mother and the fetus, and understanding them is essential for managing pregnancy-related complications.This review highlights the significant physiological changes that occur during normal pregnancy, which are essential for nurturing the developing fetus and preparing the mother for labor and delivery. These changes include: 1. **Haematological Changes**: Plasma volume increases by 50% by 34 weeks, leading to a fall in hemoglobin concentration, hematocrit, and red blood cell count. Platelet count may decrease in some women, but remains within normal limits. Iron, folate, and vitamin B12 requirements increase significantly. 2. **Cardiac Changes**: Cardiac output increases by 20-40%, with a peak at 20-28 weeks. This is achieved through an increase in stroke volume and heart rate. Blood pressure decreases in the first and second trimesters but returns to non-pregnant levels by term. Positional changes can affect cardiac output, with supine position reducing it by 25%. 3. **Renal Changes**: Systemic vascular resistance (SVR) decreases by 40%, leading to arterial under-filling. Renal blood flow and glomerular filtration rate (GFR) increase by 40-65% and 50-85%, respectively. Renal size increases by 1-1.5 cm, and hydronephrosis is common. 4. **Respiratory Changes**: Oxygen demand increases by 15%, leading to a 40-50% increase in minute ventilation. This results in a mild respiratory alkalosis. 5. **Alimentary Tract Changes**: Nausea and vomiting are common, possibly to prevent consumption of teratogenic substances. Mechanical changes in the gastrointestinal tract due to the growing uterus can lead to symptoms like reflux. 6. **Endocrine Changes**: Thyroid function and adrenal gland activity are altered, with increased production of thyroxine-binding globulin and mineralocorticoids. Pituitary gland enlargement is observed, with increased prolactin and oxytocin levels. 7. **Metabolic Changes**: Glucose metabolism adapts to shunt glucose to the fetus, leading to insulin resistance and hyperglycemia. Lipid and protein metabolism also change to meet the needs of the developing fetus. 8. **Calcium Metabolism**: Increased dietary absorption of calcium is necessary to meet fetal needs, leading to hypercalciuria and a risk of kidney stones. These changes are crucial for the health and development of both the mother and the fetus, and understanding them is essential for managing pregnancy-related complications.