This document summarizes the physiological changes that occur in a woman's body during pregnancy across multiple body systems. The cardiovascular system adapts to accommodate increased circulatory demands for the mother and fetus, including a 40% increase in cardiac output. Respiratory changes include diaphragm elevation and improved oxygen delivery. The genitourinary system experiences kidney enlargement and bladder displacement by the growing uterus. Gastrointestinal changes involve relaxation of the esophagus, stomach and intestines as well as increased risk of gallstones. The endocrine and musculoskeletal systems also adapt to support the nutritional and structural changes of pregnancy.

1. Physiological Changes in Pregnancy Sandy Warner RNC – OB, MSN

2. Adaptations Nurses must understand the normal anatomical and physiological changes in pregnancy to recognize any deviation from normal. In addition to physical changes, there are also psychological changes that occur with pregnancy.

3. Body system alterations Cardiovascular Hematological Respiratory Genitourinary Gastrointestinal Immunological Musculoskeletal Endocrine

4. Cardiovascular Cardiovascular adaptation affects all organ systems. Cardiovascular anatomy and physiology changes to accommodate increasing maternal and fetal circulatory needs.

5. Heart Anatomic changes: Heart is enlarged, displaced upward and rotates to the left. PMI (point of maximal impulse) shifts to 4th intercostal space and closer to the midclavicular line.

6. Heart sounds and rate: Audible splitting of S1 and S2; S 3 becomes audible. Benign systolic murmurs are common. Heart rate increases 15-20 beats as pregnancy progresses.

7. Cardiac Output Defined as the amount of blood pumped from the left ventricle into the aorta each minute. (heart rate x stroke volume = CO) In pregnancy increased by 40% by 36-38 wks. Influenced by: Blood volume Stroke volume Heart rate

9. Blood Pressure Due to decreased systemic vascular resistance, blood pressure is lower at end of 1st trimester and throughout 2nd, returning to baseline in 3rd trimester. Also affected by renin-angiotensin-aldosterone system from kidneys.

10. Hematological Changes Increase in WBCs and RBCs. Increase blood volume for uterus, fetus and increased perfusion of other organs, especially kidneys. Increased plasma volume ratio to RBC volume leads to hemodilution.

11. Hematological changes cont. Hypercoagulation Decreased fibrinolytic activity Platelets remain normal or might decrease slightly Increased need for iron related to RBCs

12. Respiratory Anatomic changes: Diaphragm elevation Chest expansion Capillary dilation early in pregnancy causes Engorgement of entire tract from nares to bronchi Voice changes

13. Respiratory Physiological changes: Increased need for oxygen Improved oxygen delivery Hyperventilation Compensatory respiratory alkalosis

14. Genitourinary Kidneys – increase in size and GFR. Ureters – dilate and elongate, becoming compressed by uterus. Bladder – tone decreases due to progesterone, becomes displaces as uterus grows.

15. Genitourinary Urine flow accumulates and slows. Increased renal excretion of BUN, creatinine and glucose. Decreased serum BUN, creatinine and glucose. Decreased tubular reabsorption of glucose. Increased tubular reabsoption of sodium.

16. Genitourinary Uterus – rises out of pelvis during 1st trimester. Weight increases from 70 gms to 1100 gms. Volume at term averages 5 L but may be as much as 20 L. Individual cells increase 100 fold in length by term, allowing for contractions and involution.

17. Genitourinary Cervix: Increases in mass and fluid content. 85% connective tissue and 15% smooth muscle. Ripening occurs via softening and effacement with the influence of hormones.

18. Gastrointestinal Mouth – changes in tastes, increase in saliva production, gums swell and bleed easier. Esophagus – decreased tone leads to reflux. Stomach – decreased tone and motility. Intestines – smooth muscle relaxation and decreased tone and motility - constipation

19. Gastrointestinal Esophagus, stomach and intestines move as uterus grows. Round ligament stretches as uterus expands. Gallbladder –decrease tone and motility combined with increased emptying time can cause increased risk of gallstones.

20. Gastrointestinal Hyperemesis – common in first trimester. Strong sense of smell. Increased saliva production. Can persist throughout pregnancy.

21. Immunological Placenta functions to help protect the fetus from infection with IgG. Decreased Tcell activity with pregnancy that increases susceptibility to viral infections. Immunity is enhanced by sleep/rest and decreased stress.

22. Musculoskeletal Abdominal muscles relax and pelvis tilts forward. Center of gravity shifts. Joints relax – waddling. Muscle aches from increasing weight of uterus. Posture change due to lumbodorsal curve of spine.

23. Musculoskeletal Normal weight gain 25-35#. Slight weight loss in 1st trimester from nausea and vomiting. Average 1#/wk weight gain in 2nd and 3rd trimesters.

24. Endocrine Thyroid: Function increases to meet metabolic and growth needs. Parathyroid: Helps regulate calcium, phosphorus, Vit. D and magnesium concentration. Increases in pregnancy to help skeletal growth.