Physiological & Hormonal Changes in Pregnancy
Explain the physiological changes taking place in the reproductive and endocrine system during pregnancy
Hormonal
Levels of progesterone and estrogen rise continually throughout pregnancy suppressing the hypothalamic axis
and subsequently the menstrual cycle
Trophoblast produces Human Chorionic Gonadotropin from day 8
Gestational diabetes
Gestational hypertension
Fetal-placental unit
Progesterone is first produced by the corpus luteum and then by the placenta in the second trimester
Increased human chorionic gonadotropin (β-hCG) produced by the placenta
Pancreatic insulin
Placenta produces human placental lactogen which stimulates maternal lipolysis and fatty acid metabolism.
Cardiovascular changes
Plasma volume increases; blood volume increases from 5L to 7.5L
Because of the volume increase the RBC concentration decreases → physiological anemia & hematocrit decreases
Peripheral vascular resistance decreases
Pulmonary vascular resistance decreases
Blood pressure lowers because of vasodilatation by progesterone
There is a decrease in the diastolic blood pressure
Heart rate increases, stroke volume increases, cardiac output increases
Mild hypertrophy of the myocardium
When lying down uterus presses on the IVC → less blood to right atrium → hypotension
The size of the heart increases
Physiological S3, split S1
Retention of fluid due to hormones causes edema of hands feet and ankles
Distention of abdomen shifts heart upwards and laterally
Diaphragm elevated, heart slightly shifts up and to the left
Respiratory System
Chest expands
Capillary dilatation in the entire respiratory system - in the upper respiratory tract : estrogen causes increased
vascularization → sinus congestion and epistaxis - nasal stuffiness - voice changes
Hyperventilation - mild physiological alkalosis
Lungs : uterus presseson diaphragm → mild dyspnea Progesterone relaxes ligaments → increased tidal volume
→ decreased CO2 → mild respiratory alkalosis
Genital changes
Uterus enlarges - height and weight increase - presses on pelvic veins - pedal edema
Uterus is rotated towards the right - dextrorotation
Lower segment of the uterus is formed
Cervix - edematous, congested, soft, mucus plug forms (operculum), cervical secretions increase
Vulva - increased vascularity and varicosities form
Vagina - increased vascularity, soft, moist and bluish
Ovary - increased vascularity, one contains the corpusluteum
Pelvic ligaments - relax; Pelvic joints relax, pelvis
Kidney
Increased blood flow to kidneys → increased GFR → increased urinary output → increased urinary frequency
Kidney size increases - size of calyces and renal pelvis increase → physiological hydronephrosis; progesterone causes
hypomotility of ureters and physiological hydroureter results - urinary stasis → chance of UTI
GIT
Hormonal changes produce smooth muscle relaxation → decreased peristalsis → constipation and bloating of the abdomen
Relaxation of cardiac sphincter of the esophagus → gastric reflux and heartburn
Morning sickness, nausea and pica
Breasts
Develop
Tingling, fullness and tenderness
Due to prolactin by anterior pituitay
Due to malanocyte stimulating hormone produced by anterior pituitary areola darkens, linea alba darkens called linea nigra
Thyroid
Increased thyroid hormones → increased BMR
CNS
Estrogen and progesterone cause irritability, anxiety and depression, mental confusion and decreased concentration.
Fatigue and sleep deprivation can occur
Spines
Due to enlarged abdomen centre of gravity shifts - lordosis → low back pain, diastasis recti (rectus abdominis muscles separate)
Pelvis
Placenta produces progesterone, and relaxin → relaxes the ligaments of the sacroiliac joint and symphysis pubis - waddling gait,
pain in the coccyx and ribs too.
More . . .
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