MBChB student JKUAT

1. PHYSIOLOGICAL
CHANGES DURING
PREGNANCY
Harrison Mbohe, MBChB Level 4 JKUAT

2. GENITAL ORGANS
VULVA
•Oedematous
•More vascular
•Superficial varicosities, especially in
multiparous women
•Labia minora- hypertrophied and pigmented

3. VAGINA
• Hypertrophies
• Oedematous
• Jacquemier’s Sign – increased blood supply to the venous
plexus on vaginal walls that confers a bluish colouration on the
mucosa
• Increased length of the anterior wall
• Secretions - copious, thin and cloudy white (due to marked
epithelial and bacterial exfoliation)
• pH – acidic (3.5-6.6)
• Navicular cells predominate (small intermediate cells in
clusters with elongated nuclei)

4. UTERUS
• Enormous growth. At term it weighs approx. 1000g and measures
approx. 35cm in length. Its capacity increases 500 – 1000 fold.
Body
• Marked hypertrophy of muscle fibres with limited addition of new
muscle fibres
• Elongation of muscle fibres beyond 20 weeks; becomes soft and
elastic.
• Increased no. and size of supporting fibrous and elastic tissues.
• Marked spiralling of arteries reaching max at 20 weeks & thereafter
straightening out.
• Increased diameter of uterine arteries by 2 fold and increased blood
flow into them by 8 fold

5. • Uterine veins become dilated and valveless.
• Opening up of numerous lymphatic channels.
• Findus enlarges more than the body
• Pyriform shape at early months  becomes globular at 12
weeks  returns to Pyriform shape by 28 weeks  changes to
spherical beyond 36 weeks
• Braxton hick contractions
Isthmus
• Hypertrophy and elongation in trimester; increases 3 fold its
normal length.
• Becomes softer

6. Cervix
•Hypertrophy and hyperplasia of the elastic and
connective tissue.
•Goodell’s sign (softening of the cervix).
•Increased vascularity.
•Marked hypertrophy & hyperplasia of the glands that
occupy half of the cervical mucosa.
•Marked proliferation of the endocervical mucosa with
downward extension beyond squamocolumnar jxn.
•Secretions – copious and tenacious (physiological
leucorrhoea in pregnancy)

7. •Suspended ovarian
and uterine cycles of
normal menstruation

8. BREASTS
• Changes more pronounced in primies.
• Increased breast size (marked hypertrophy & proliferation of the
ducts and alveoli; marked proliferation of connective tissue stroma
and prominence of myoepithelial cells).
• Increased vascularity.
• Axillary tail becomes enlarged and painful.
• Nipples become larger, erectile and deeply pigmented.
• Secretions – sticky at about 12 weeks, later on become thick &
yellowish.

9. CUTANEOUS CHANGES
•Chloasma gravidarum – increased pigmentation
around the cheeks, forehead and around the eyes.
•Linea nigra – linear hyperpigmentation that appears
as a brown-black streak that runs vertically, along the
midline of the abdomen from the pubis to the
umbilicus.
•Striae gravidarum – stretch marks below the
umbilicus and sometimes over the thighs and breasts.

10. CVS & HEMATOLOGICAL
CHANGES
•Marked increase in blood volume – starts at approx. 6
weeks and expands rapidly thereafter to a max of 40 – 50
% above normal at 30-32 weeks.
•Increased venous capacitance.
•Increased erythropoiesis.
•Increased HR by averagely 15 bpm
•Increased CO by approx. 40%
•Increased stroke volume by approx. 25-30%
•Slight decrease in systemic arterial pressure

11. •Progressive increase in venous pressures in the lower
extremities due to compression of the IVC by the gravid
uterus.
•Decreased peripheral vascular resistance with a slight
increase towards term due to effect of vasodilators.
•Increased blood flow to the uterus, kidneys, skin and
breasts
•Systolic ejection murmurs – detected in >90% of gravid
women.
•Devpt of dizziness, syncope and light headedness.
•S1 may be split with increased loudness of both portions.
S3 may be louder.

12. •ECG changes
• 15-200 shift to the left in the electrical axis
• ST segment depression
• T wave flattening/inversion
• No changes in the P wave and QRS complex
•MCV increases by 20 – 30% resulting in decreased MCHC
and Hct leading to haemodilution.
•Neutrophilic leucocytosis due to increased oestrogen and
cortisol.
•Modulation away from cytotoxic immune responses
towards humoral and innate immune responses.

13. •Total protein increases from 180g – 230g
•Fibrinogen increases by 50%.
•Gestational thrombocytopenia – remains within normal
range.
•ESR increases 4 fold.
•Fibrinolytic activity is depressed.
•Increased activity of the clotting factors – X, IX, VIII & I
•Clotting time remains unaffected.

14. RESPIRATORY CHANGES
• Elevation of diaphragm by the gravid uterus by approx. 4cm.
• Widening of the subcostal angle.
• Slight increase of chest diameter and circumference.
• 20% decrease in RV & FRC + 5% decrease in total lung
volume.
• Respiratory rate remains unchanged.
• 30 – 40% increase in tidal volume.
• Gravid women also tend to become dyspnoeic.
• Nasal stiffness + increased nasal secretions due to mucosal
hyperaemia.

15. RENAL CHANGES
• Enlargement and dilatation of the kidneys and the urinary collecting system.
• Increased renal blood flow – up to 75% at term.
• Increased GFR by approx. 50%.
• Increased urinary glucose excretion (not associated with glycaemic pathology).
• No significant increase in urinary protein loss.
• Sodium metabolism remains unchanged.
• Plasma renin increases 10 fold.
• Angiotensinogen and angiotensin increase approx. 5 fold.
• Urinary frequency.
• Stress urinary incontinence in 20% of women.
• Increased incidence of pyelonephritis due to urinary stasis with asymptomatic
bacteriuria.
• Reduced serum levels of creatinine and BUN

16. RENAL CHANGES
• Enlargement and dilatation of the kidneys and the urinary collecting system.
• Increased renal blood flow – up to 75% at term.
• Increased GFR by approx. 50%.
• Increased urinary glucose excretion (not associated with glycaemic pathology).
• No significant increase in urinary protein loss.
• Sodium metabolism remains unchanged.
• Plasma renin increases 10 fold.
• Angiotensinogen and angiotensin increase approx. 5 fold.
• Urinary frequency.
• Stress urinary incontinence in 20% of women.
• Increased incidence of pyelonephritis due to urinary stasis with asymptomatic
bacteriuria.
• Reduced serum levels of creatinine and BUN

17. GIT CHANGES
• Displacement of the stomach and intestines by the gravid uterus with no changes
in sizes.
• Enlargement of the portal vein due to increased blood flow.
• Generalized smooth muscle relaxation mediated by progesterone resulting in
reduced lower esophageal sphincter tone, reduced GI motility and impaired gall
bladder contractility.
• GERD due to imbalanced lower intraesophageal pressures and increased
intragastric pressures + reduced lower esophageal sphincter tone.
• Gall stones and cholestasis of bile salts due to reduced gall bladder contractility
and oestrogen mediated inhibition of intraductal transportation of bile acids.
• Nausea and vomiting due to elevated P4, HCG and relaxation of gastric smooth
muscle.
• Hyperemesis gravidarum which results in weight loss, ketonemia or electrolyte
imbalance.

18. • Pica – appetite/cravings for substances which are largely non-
nutritive.
• Constipation due to mechanical obstruction of the colon by
the gravid uterus, reduced motility and increased water
absorption.
• Generalized pruritus due to intrahepatic cholestasis and
increased bile acid serum concentrations.
• Gingival disease.
• Haemorrhoids due to constipation and elevated venous
pressures.
• Elevated ALP due to increased placental production.
• ALT, AST, GGT & bilirubin are largely unchanged or are
slightly lower.

19. ENDOCRINE CHANGES
• Moderate thyroid enlargement which doesn’t produce thyromegaly or
goitre.
• Transient increase in free t4 – 20 to increased HCG levels that has TSH like
activity. Levels of t4 normalize after trimester 1 due to reduced HCG levels.
• Increased total t3 and t4 due to oestrogen induced hepatic synthesis of TBG.
• Free t3 and t4 are unchanged.
• Increased serum cortisol due to oestrogen induced hepatic synthesis of
CBG.
• Increased ACTH.
• Marked increased levels of aldosterone.
• Increased deoxycortisone levels.
• Reduced DHEAS due to hepatic uptake and subsequent conversion to
oestrogen

20. METABOLIC CHANGES
CARBOHYDRATE METABOLISM
•Increased insulin resistance, hyperinsulinemia and
hyperglycaemia due to influence of placental lactogen
secreted in proportion to placental mass and progesterone.
•Increased hepatic glycogenesis
•Reduced gluconeogenesis.
•Constant drainage of maternal glucose by the fetoplacental
unit leads to maternal hyperglycaemia during periods of
fasting.

21. LIPID METABOLISM
•Increase in circulating levels of lipids,
lipoproteins and apolipoproteins.
•Central lipogenesis dominates in early
pregnancy.
•Lipolysis dominates in late pregnancy triggered
possibly by maternal fasting hypoglycaemia.
•All lipid levels normalize after delivery in a
process accelerated by breastfeeding

22. PROTEIN METABOLISM
•Increased intake and utilization
of proteins 1 kg above the
normal non-pregnancy

23. MUSCULOSKELETAL CHANGES
• Compensatory lumbar lordosis – helps to keep woman’s CoG over the legs
which the gravid uterus has shifted anteriorly.
• Lower back pain due to the lumbar lordosis.
• Diastasis recti – physiological separation of rectus abdominis due to raised
intraabdominal pressures from the enlarging uterus.
• Unsteady gait due to relative laxity of ligaments influenced by progesterone
and relaxin; separation of the pubic symphysis at approx. 28-30 weeks and
an altered CoG.
• Reduced maternal total calcium, compensated for by raising maternal
parathyroid hormone.
• Skeleton well maintained despite elevated PTH levels by the counter
regulatory function of calcitonin

24. OPHTHALMIC CHANGES
•Blurred vision due to increased thickness of the
cornea associated with fluid retention and
reduced intraocular pressures. This regresses
within the first 6-8 weeks post partum.

25. THANK
YOU