Physiology and Signs of Pregnancy

Physiology and Signs of Pregnancy

1. PRESENTED BY:
ANISH DHAKAL

2. Genital Organs:
Vulva
◦Edematous and more vascular
◦Labia minora are pigmented and hypertrophied
Vagina
◦Hypertrophy of walls
◦Edematous and more vascular (Jacquemier’s sign)
◦ Length of anterior vaginal wall
Secretion
◦Copious, thin and curdy white(exfoliated cells and bacteria)
◦pH becomes acidic(conversion of glycogen into lactic acid)

3. Uterus
Growth of uterus:
Non-pregnant state At term
Weight 60gm 900-1000gm
Length 7.5cm 35cm
Capacity 5-10ml  By 500-1000 times

4. Body of the uterus:
Enlargement of uterus takes place which is affected by:
◦Changes in the muscles:
◦Hypertrophy and hyperplasia
◦Stretching
Increased number and size of supporting fibrous and
elastic tissue

5. Vascular system:
◦Uterine and ovarian arteries
◦Hypertrophy of uterine arteries
◦Vasodilatation due to estradiol and progesterone
◦Vascular changes mostly takes place at placental site
Shape:
◦Pyriform to globular at 12
th
weeks.
◦Pyriform/ ovoid by 28
th
weeks.
◦Spherical beyond 36
th
weeks.

6. Contractions:
•First described by Braxton- Hicks
◦Irregular, spasmodic, infrequent and painless from
the very early week
◦Patient is unconscious about contraction
◦Near term  frequent contraction with 
intensity discomfort to patient
◦Painful uterine contraction at labour

7. Cervix
Increased vascularity & edema of cervix softening & cyanosis-
Goodell’s sign
Rearrangement of collagen rich connective tissue
Hypertrophy & hyperplasia of cervical glands
Mucus plug formation
Marked endocervical mucosa proliferation-appears as cervical
erosion
Squamous cells hyperactive stimulating basal cell hyperplasia

8. Breast Size:
Hypertrophy and proliferation of ducts and alveoli
 vascularity  appearance of bluish vein running
under the skin
Striation due to stretching of cutis
Nipples and Areola:
Larger, erectile and deeply pigmented
Secretion:
Colostrum can be squeezed out at about 12
th
week which
is sticky
By 16
th
week becomes thick and yellowish

9. Cutaneous changes
Face(Chloasma gravidarum or mask of
pregnancy):
◦Pigmentation around cheek, forehead and eyes
Striae gravidarum
◦Below umbilicus sometimes over thigh and breast
Linea nigra
◦Brownish black pigmentation
◦Present in midline extending from xiphisternum to symphysis
pubis
Angiomas/ vascular spiders (minute, red elevations on skin)
Palmar erythema

10. Weight Gain
Reproductive weight gain: 6kg Net maternal weight gain: 6kg
Fetus: 3.3kg Increase in blood volume: 1.3kg
Placenta: 0.6kg Increase in extracellular fluid: 1.2kg
Liquor: 0.8kg
Uterus: 0.9kg
Breasts: 0.4kg
Accumulation of fat and proteins: 3.5kg
1
st
trimester- 1kg
2
nd
trimester- 5kg
3
rd
trimester- 5kg
Total: 11kg

11. Body water Metabolism
Amount of water retained at term 6.5L
Pregnancy is state of hypervolemia
Active retention of Sodium, Potassium and water
Causes:
 estrogen and progesterone
 renin angiotensin activity
Atrial natriuretic peptide & BNP

12. HEMATOLOGICAL CHANGES
Increase in
◦White cell count
◦Erythrocyte sedimentation rate (ESR)
◦Fibrinogen concentration
◦Factors VII, VIII, IX, X and XII
Non pregnant Pregnancy (term) Change
Blood volume(ml) 4000 5500 + 30-40%
Plasma volume(ml) 2500 3750 +40-50%
Red cell volume(ml)1400 1750 + 20-30%
Total Hb (gm) 475 560 + 18-20%
Haematocrit 38% 32% Diminished

13. Cardiovascular system
Anatomically heart is pushed upwards and outwards with slight rotation to left
Peripheral vasodilation
 heart rate
 stroke volume
 cardiac output
Supine hypotension (due to impairment of venous return by gravid uterus)
 mean arterial pressure
 peripheral resistance

14. Respiratory Changes
Transverse diameter thoracic cage  by 2cm
Oxygen consumption  by 45ml/min
 tidal volume
 pCO
2

 pO
2

pH alters
Pregnancy is in state of respiratory alkalosis

15. Renal Changes
Vasodilation   blood flow(50-75%)
 glomerular filtration rate (GFR) (50%)
Dilation of renal pelvis, calyces and ureter
increase frequency of micturition at 6-8 wks which subsides after
12 wks
In late pregnancy frequency reappears due to pressure on
bladder as presenting part descends
stress urinary incontinence occurs weakness of urethral
sphincter

16. GI system changes
Gums become soft,congested and may bleed to touch
Muscle tone and motility of entire GIT diminished
heart burndecrease in tone of lower esophageal sphincter
Diminished gastric secretion and delayed emptying time of
stomach

17. Endocrine changes
 prolactin concentration
 corticosteroids concentration
 TSH in early pregnancy
 FT4 in late pregnancy
HCG is produced
Insulin resistant

18. 1
st
trimester
Subjective symptoms
Amenorrhoea
Morning sickness
Frequency of micturation
Breast discomfort
fatigue
Objective signs
•Breast changes
•Pelvic changes
•Uterine signs

19. Amenorrhea:
◦cyclic bleeding may occur, which is scanty and lasting for
shorter duration
Morning sickness:
◦appears soon following the missed period
◦intensity varies from nausea, loss of appetite or even vomiting
Frequency of micturition due to:
◦Resting of bulky uterus on the fundus of bladder
◦Congestion of bladder mucosa
◦Change in maternal osmoregulation

20. ◦Breast changes: evident between 6-8 weeks
and nipple and areola become more pigmented
◦Per abdomen: uterus remain pelvic organ until
12
th
week and just felt per abdomen as a supra
pubic bulge

21. Pelvic changes
Jacquemier’s or Chadwick’s sign- dusky hue of
vestibule and anterior vaginal wall visible at about 8
th

week of pregnancy due to local vascular congestion.
Vaginal signs-
◦Walls softens
◦Copious mucoid discharge at 6
th
week
◦↑pulsation felt through lateral fornices at 8
th
week called
Osiander’s sign.
Cervical signs-
◦Soft at 6
th
week(Goodell’s sign)
◦On speculum exam. bluish discoloration seen

22. Uterine signs
Size, shape, symmetry:
◦enlarged to size of :
◦hen’s egg at 6
th
week,
◦cricket ball at 8
th
week
◦fetal head by 12
th
week.
◦Feels soft and elastic
Hegar’s sign:
◦Upper part of body of uterus is enlarged
◦Lower part of body is empty and soft
◦Cervix is comparatively firm
Palmer sign:
◦Regular rhythmic uterine contraction elicited during
bimanual examination

24. 2
nd
trimester
Symptoms
Amenorrhoea continues
“Quickening”(feeling of life)
◦Perception of active fetal
movements.
◦Usually at 18
th
week.
Progressive enlargement of
lower abdomen
G/E
•Choloasma-
pigmentation over
forhead and cheek
•Breast changes
•Enlarged with
prominent veins
•Secondary areola
•Colostrum thick and
yellowish

25. Abdominal examination
Inspection
◦Linea nigra visible from symphysis pubis to
ensiform cartilage.
◦Pink and white striae visible in lower abdomen
Palpation
◦Increased fundal height with progressive
enlargement of uterus.
◦Uterus feels soft and elastic and ovoid shape
◦Braxton- Hicks contractions are evident
◦Palpation of fetal parts and active fetal
movement can be felt at 20
th
week.

26. Level of fundus uteri at different
weeks.

27. Third Trimester
Symptoms
◦Amenorrhea persists
◦Enlargement of abdomen
◦Lightening: due to
engagement of the presenting
part
◦Frequency of micturition
reappears
◦More pronounced fetal
movement
•Signs
–Cutaneous changes: 
pigmentation and striae
–Uterine shape is changed from
cylindrical to spherical
–Symphysis fundal height
–Fetal movement are easily felt
–Palpation of fetal part
–FHS is heard distinctly in
corresponding to presentation and
position of the fetus

28. References
Dutta Dc. Textbook of obstetrics. 8
th
edition
Williams Obstetrics, 24
th
edition