Physiological Changes in Pregnancy

Physiological Changes in Pregnancy

·        During pregnancy there are progress anatomical and physiological changes.

·        These changes do not only occur at the genital organs but also to all the system of the body.

·        This is due to increasing demands of the growing fetus.

I. Changes in genital organs

1. Vulva

·        It becomes edematous and hyperemic.

·        The labia minora become pigmented and hypertrophied

2. Vagina

·        It becomes hypertrophied vascular and edematous

·        The vaginal secretions becomes copious, thin and curly white

·        The ph becomes more acidic.

3. Uterus

·        There is increase in size of uterus

·        It measures 35 cms in length and 900-1000 gms

·        Changes occur in all the parts of uterus.

·        The uterine muscles undergo hypertrophied and hyperplasia.

·        The fondues enlarged more than the body if the uterus.

·        The 3 distinct layers of uterus muscles can be made out.

·        In a turn the uterus differentiates into an active upper segment which is more muscular and a passive lower segment which is least muscular.

·        The cervix is deviated to the left side (levo-rotation), bringing it closer to the ureter due to lateral obliquity.

II. Breast

·        There is increase in the size of the breast due to hypertrophy and proliferation of the ducts alveoli.

·        The vascularity increase which result in the appearance of bluish veins running under the skin.

·        The nipples becomes larger, erectile and are deeply pigmented

·        The sebaceous glands which remains invisible in the non-pregnant state becomes hypertrophied over the areola during pregnancy and are called as Montgomery‘s tubercles

·        Secondary areola is seen in the 2nd trimester

·        Secretions may also been seen at about 12 weeks of pregnancy

·        Breast weight is increased approximately to 500-800 gm

III. Endocrine system

·        Changes are brought about by progesterone, estrogen and relaxin hormones

a. Effects of progesterone

·        Reduction in tone of smooth muscles resulting in nausea, reduced peristalsis, constipation, bladder toned is decreased, dilation of veins and decreased diastolic pressure

·        Increase in body temperature

·        Increased storage of fats

·        Development of breast, alveolar and glandular milk producing cells

b. Effects of estrogen

·        Increased growth of uterus and breast ducts

·        Increased levels of prolactin for lactation

·        Maternal calcium metabolism

·        Higher levels may result in increased vaginal glycogen resulting in “thrush”.

c. Effects of relaxin

·        Replacement of collage in pelvic joints, capsules, cervix, resulting in greater extensibility and pliability

·        Inhibition of myometrial activity

·        Helps in distension of uterus and provides additional supporting connective tissues.

·        Has a role in cervix ripening

IV. Cutaneous changes

·        There is formation of chlosma gravidarum or pregnancy mark in the form of pigmentation around the cheek which is patchy or diffused and it disappears after delivery

·        It also shows formation of linea nigra which is a brownish black pigmentation in the midline of the abdomen stretching from the xiphisternum to the pubic symphysis. It usually disappears after delivery.

·        Striae gravidarum are slightly depressed linear marks with varying length and breath. These are seen just below the umbilicus

·        These are pinkish during delivery which becomes glistening white after pregnancy and is then called as striae albicans

V. Weight gain

·        A pregnant lady puts on about 10-12 kg of weight

·        In early pregnancy the lady may loose weight due to nausea and vomiting but later the weight gain is progressively increased to about 2 kg every month

VI. CVS changes

·        Increase in blood volume by 40%

·        Increase in plasma level than red cells and Hb level falls by 80%. This is called as dilution anemia or physiological anemia due to pregnancy

·        During 3rd trimester, the weight of fetus may compress the aorta and IVC against the lumbar spine in lying position causing dizziness, unconsciousness and is called as pregnancy hypotensive syndrome.

·        Increase in cardiac output by 40%

·        Stroke volume increased by 30%

·        Heart rate increased by 30%

·        Heart rate increased by 15 beats/min

VII. Respiratory system

·        Respiratory rate increases from 15-18 breath/min (hyperventilation)

·        Alveolar ventilation increases

·        Tidal volume increases up to 40%

·        Diaphragm is raised by 40 mm

·        Chest diameter is increased by 20 mm

·        CO₂ tension is decreased

·        PaO₂ – 92 mm of Hg

·        PaCO₂ – 30 mm of Hg

VIII. GIT and urinary system

·        respiratory rate increases from 15 to 18 breath/min(Hyperventilation)

·        Alveolar ventilation increases.

·        Tidal volume increases up to 40%

·        Diaphragm is raised up to 40mm

·        Chest diameter is increased by 2mm

·        CO₂ tension is decreased

·        PaO₂—92mm of Hg

·        PaCo₂ __ 30mm of Hg

VIII. GIT and Urinary system:

·        Nausea and vomiting due to response by human chronic Gonadotrophin (HCG)

·        Delayed gastric emptying and thus shows constipation

·        Increased concentration of bile in gall bladder

·        There is increased in the size and weight of kidney and dilation of the renal pelvis

·        Dilation of uterus causes pooling and stagnation of urine resulting in U.T.I.

IX. Musculoskeletal system

·        Increased joint laxity

·        Increased lumbar lordosis due it change in COG and pelvic tilting

·        The distance between the two rectus abdominal muscles widens and the linea alba may split under the strain called as Diastasis Recti

·        Edema of ankle due to water retention

·        Compression of nerves causing carpel tunnel syndrome

X. Psychological and emotional changes

·        Mood swings

·        Depression

·        Anxiety