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 12th
weeks.
◦Pyriform/ ovoid by 28th
weeks.
◦Spherical beyond 36th
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 12th
week which
is sticky
By 16th
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
1st
trimester- 1kg
2nd
trimester- 5kg
3rd
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
 pCO2
 pO2
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. 1st
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
12th
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 8th
week of pregnancy due to local vascular congestion.
Vaginal signs-
◦Walls softens
◦Copious mucoid discharge at 6th
week
◦↑pulsation felt through lateral fornices at 8th
week called
Osiander’s sign.
Cervical signs-
◦Soft at 6th
week(Goodell’s sign)
◦On speculum exam. bluish discoloration seen

22. Uterine signs
Size, shape, symmetry:
◦enlarged to size of :
◦hen’s egg at 6th
week,
◦cricket ball at 8th
week
◦fetal head by 12th
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. 2nd
trimesterSymptoms
Amenorrhoea continues
“Quickening”(feeling of life)
◦Perception of active fetal
movements.
◦Usually at 18th
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 20th
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. 8th
edition
Williams Obstetrics, 24th
edition