Chapter 4: Physiological Aspects of Pregnancy

Pregnancy initiates systemic adaptations across virtually every organ system, primarily orchestrated by hormonal changes including human chorionic gonadotropin, estrogen, progesterone, and relaxin. The reproductive system undergoes dramatic expansion, with uterine capacity and weight increasing approximately fifty-fold to accommodate fetal development. Cardiovascular adjustments include significant blood volume expansion to perfuse both maternal and fetal tissues, though plasma volume increases disproportionately to red blood cell production, creating a dilutional anemia. Respiratory function shifts from abdominal to thoracic breathing patterns as the enlarging uterus displaces the diaphragm. Renal system changes elevate glomerular filtration rates and increase urinary frequency while enhancing susceptibility to infection. Gastrointestinal motility decreases due to hormonal influences, resulting in common complaints including nausea, constipation, and heartburn. Musculoskeletal changes involve ligament softening and spinal curvature alterations that affect gait and balance. Integumentary manifestations include hyperpigmentation patterns and stretch mark formation. The chapter emphasizes preconception health optimization, including achievement of normal body mass index, folic acid supplementation, vaccination review, and identification of teratogenic exposures. Pregnancy diagnosis relies on a hierarchical classification system involving presumptive signs such as amenorrhea, probable objective signs including cervical changes and positive tests, and positive diagnostic findings through ultrasound or fetal heart tone auscultation. Estimated date of delivery calculation follows established protocols such as Naegele's rule based on last menstrual period dating. Prenatal nursing care encompasses systematic assessments performed at increasing frequencies as pregnancy progresses, including vital signs, weight monitoring, fundal height measurement, and fetal surveillance. Comprehensive screening protocols address first trimester baseline laboratory studies, second trimester gestational diabetes screening, third trimester group B streptococcus detection, and ongoing assessment for intimate partner violence. Patient education focuses on managing normal pregnancy discomforts and recognizing danger signs requiring immediate medical evaluation.