Anatomical and physiological changes in pregnancy 1
Introduction Reproductive tract Uterus, vagina, cervix, fallopian tubes. Skin Breast Central nervous system Cardiovascular system Respiratory system Urinary system 2
Gastrointestinal tract Endocrine system Musculoskeletal sysstem Haematological changes Metabolic changes Immunological changes. 3
IntroducTon The anatomical, physiological, and biochemical adaptations to pregnancy are profound. Begin soon after fertilization and continue throughout gestation Response to physiological stimuli provided by the fetus and placenta. 4
Physiological adaptations of normal pregnancy can be misinterpreted as pathological Changes unmask or worsen pre-existing disease. Understanding of these adaptations to pregnancy a major goal of obstetrics. 5
Reproductve TracT Uterus Non-gravid uterus is an almost-solid structure weighing about 70 g and with a cavity of 10 mL or less. During pregnancy: Muscular organ of suFcient capacity to accommodate the fetus, placenta, and amniotic ±uid. The total volume of the contents at term averages about 5 L. At term, the organ weighs approximately 1100 g. 6
Uterine enlargement involves stretching and marked hypertrophy of muscle cells . By term, they are only 1 to 2 cm or even less in thickness. Muscular sac with thin, soft wall through which the fetus can be palpated. Uterine hypertrophy early in pregnancy is stimulated by the action of estrogen and progesterone . 7
Uterine Size, Shape, and Position First trimester: the uterus maintains its original pear shape Week 12: Globular form. Subsequently, the organ increases more rapidly in length than in width and assumes an ovoid shape. By the end of 12 weeks, the uterus has become too large to remain entirely within the pelvis. It displaces the intestines , and continues to rise ultimately reaching almost to the liver. 8
With ascent of the uterus from the pelvis, it usually undergoes rotation to the right. This dextrorotation likely is caused by the rectosigmoid on the left side of the pelvis. The abdominal wall supports the uterus . In supine position , the uterus falls back to rest on the vertebral column and the adjacent great vessels, especially the inferior vena cava and aorta. 9
Contractility Early pregnancy: Uterus undergoes irregular contractions that are normally painless. During the second trimester, Braxton Hicks contractions appear unpredictably and sporadically and are usually non-rhythmic. Late in pregnancy, these contractions may cause some discomfort and account for so- called false labour . 10
Utero-placental Blood Flow Placental perfusion is dependent on total uterine blood Fow, which is principally from the uterine and ovarian arteries.
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- Winter '16
- Bill Oyieke