This document describes the physiological changes that occur during pregnancy across multiple body systems. It notes that pregnancy causes progressive anatomical, physiological and biochemical changes not only to the genital organs but all body systems as the body adapts to the demands of the growing fetus. Some key changes include increased size and vascularity of the uterus, softening of the cervix, changes in the breasts like increased size and secretion of colostrum, skin pigmentation changes, and weight gain of approximately 11 kg. The document also outlines methods for diagnosing and differentially diagnosing pregnancy.

1. PHYSIOLOGICAL CHANGES IN
PREGNANCY
Dr. Kilindo, MD
Obstetrics and Gynaecology I (CMT 05104)
Kibondo Clinical Officer Training Centre

2. Learning Objectives
a) Describe physiological changes in pregnancy
b) Identify clinical features of pregnancy
c) Establish diagnoses of pregnancy
d) Request routine investigations for a normal
pregnancy

3. Introduction
•During pregnancy there is progressive anatomical,
physiological and biochemical change not only
confined to the genital organs but also to all
systems of the body.
•Its basically a phenomenon of maternal adaptation
to the increasing demands of the growing fetus.
•Its better for clinician to be aware of the changes to
avoid misinterpretation of these physiological
adaptations of normal pregnancy as pathological.

4. The changes..
1. Genital Organs
•Vulva – oedematous, more vascular, labia minora
pigmented and hypertrophied.
•Vagina – walls hypertrophied, oedematous and
more vascular. Increased vascularity causes bluish
discoloration of the mucosa (Chadwick’s
sign/Jacquemier’s sign).
•Secretion: The secretion becomes copious, thin and
curdy white due to marked exfoliated cells and
bacteria. The pH becomes acidic (3.5–6) due to
Lactobacillus acidophilus, high estrogen level.

5. 2. Uterus
•Grows during pregnancy. Weighs about 60 g in non
pregnant, at term, weighs 900–1,000 g
•The enlargement of the uterus is affected by the
following factors:
(1) Hypertrophy and hyperplasia due to hormones —
estrogen and progesterone
(2) Stretching

6. CERVIX
•There are marked hypertrophy and hyperplasia of
the glands which occupy about half the bulk of the
cervix.
•This lead to marked softening of the cervix (Hegar’s
sign/Goodell’s sign) which is evident as early as 6
weeks.

7. OVARY
•The growth and function of the corpus luteum
reaches its maximum at 8th week when it measures
about 2.5 cm and becomes cystic.
•Hormones—estrogen and progesterone—secreted
by the corpus luteum maintain the environment for
the growing ovum before the action is taken over by
the placenta (at about 12th week).
•These hormones not only control the formation and
maintenance of decidua of pregnancy but also
inhibit ripening of the follicles.

8. 3. BREASTS
•Changes best evident in primes.
•Breasts increase in size due to marked hypertrophy
and proliferation of the ducts (estrogen) and the
alveoli (estrogen and progesterone) which are
marked in the peripheral lobules.
•The nipples become larger, erectile and deeply
pigmented.
•Variable number of sebaceous glands (5–15) which
remain invisible in the nonpregnant state in the
areola, become hypertrophied and are called
Montgomery’s tubercles.

9. •Those are placed surrounding the nipples.
•Their secretion keeps the nipple and the areola
moist and healthy. An outer zone of less marked
and irregular pigmented area appears in second
trimester and is called secondary areola.
•Secretion (colostrum) can be squeezed out of the
breast at about 12th week which at first becomes
sticky.
•The demonstration of secretion from the breast of a
woman who has never lactated is an important sign
of pregnancy.

10. 4. CUTANEOUS (SKIN) CHANGES
•Face (chloasma gravidarum or pregnancy mask): It
is an extreme form of pigmentation (cheek,
forehead eyes).
•Patchy or diffuse; disappears after delivery.
•Linea nigra: It is a brownish black pigmented area in
the midline stretching from the xiphisternum to the
symphysis pubis.
•The pigmentary changes are probably due to
melanocyte stimulating hormone from the anterior
pituitary or estrogen and progesterone in those
taking oral contraceptives.

11. •Striae gravidarum, striae albicans. Apart from the
mechanical stretching of the skin, increase in
aldosterone
•Apart from pregnancy, it may form in cases of
generalized edema, marked obesity or in Cushing
syndrome.
•OTHER CUTANEOUS CHANGES: Vascular spider and
palmar erythema which are due to high estrogen
level.

12. 5. WEIGHT GAIN
•The total weight gain during the course of a
singleton pregnancy for a healthy woman averages
11 kg.

14. •During pregnancy, the amount of water retained at
term is about 6.5 liters. The water content of the
fetus, placenta and amniotic fluid is about 3.5 liters.
Pregnancy is a state of hypervolemia. There is
active retention of sodium (900 mEq), potassium
(300 mEq) and water.

15. 6. Haematological Changes
• Plasma volume increases by 45-50%, beginning by
the sixth week-marked in the second trimester
•RBC mass increases by 20-35%. Moderate erythroid
hyperplasia in bone marrow.
•Disproportionate increase in plasma volume over
RBC volume leads to haemodilution
•Despite erythrocyte production there is a
physiologic fall in the haemoglobin and haematocrit
readings. (Physiological anaemia of pregnancy.)
•There is an increase in white cell count, erythrocyte
sedimentation rate (ESR), and fibrinogen
concentration.

16. 7. Cardiovascular System
•Heart rate increases by 10-20%
•Stroke volume increases by 10%
•Cardiac output (HR X SV) increases by 30-50%
•Mean arterial blood pressure decreases by 10%
•Peripheral resistance decreases by 35%

17. 8. Respiratory System
•Pco2 decreases by 15 – 20%
•Po2 increases slightly
•Oxygen availability to the placenta and tissues
improves
•pH alters little
•Bicarbonate excretion increases

18. 9. Renal System
•Renal blood flow increases 60 – 75%
•Glomerular filtration rate increases by 50%
•Clearances of most substances is enhanced
•Plasma creatinine, urea and urate are reduced
•Glycosuria is normal

19. 10. Endocrine System
•Oestrogen and progesterone increase
•Prolactin concentration increases markedly
•Human chorionic gonadotrophin hormone is
increased
•Insulin resistance develops
•Corticosteroid concentrations increase

20. CLINICAL FEATURES AND DIAGNOSING OF
PREGNANCY
•Positive or absolute signs:
•(1) Palpation of fetal parts and perception of active
fetal movements by the examiner at about 20th
week
•(2) Auscultation of fetal heart sounds
•(3) Ultrasound evidence of embryo as early as 6th
week and later on the fetus
•(4) Radiological demonstration of the fetal skeleton
at 16th week and onwards.

21. •Presumptive symptoms and signs: It includes the
features mainly appreciated by the women.
•(1) Amenorrhea
•(2) Frequency of micturition
•(3) Morning sickness
•(4) Fatigue
•(5) Breast changes
•(6) Skin changes
•(7) Quickening.

22. • Probable signs:
• (1) Abdominal enlargement
• (2) Braxton-Hicks contractions
• (3) External ballottement
• (4) Outlining the fetus
• (5) Changes in the size, shape and consistency of the uterus
• (6) Jacquemier’s sign
• (7) Softening of the cervix
• (8) Osiander’s sign
• (9) Internal ballottement
• (10) Immunological test.

23. DIFFERENTIAL DIAGNOSIS OF
PREGNANCY
•Uterine fibroid
•Cystic ovarian tumor
•Encysted tubercular peritonitis
•Hematometra
•Distended urinary bladder.

24. Routine investigations for normal pregnancy
•Pregnancy tests (hCG assays in urine or serum)
•Ultrasound

25. •Any question?

26. References
•DC Dutta’s textbook of Obstetrics 8th Edition
•Baker, P. & Monga, A. (2006). Obstetrics by Ten
Teachers (18th Ed.). London: Hodder Arnold.
•DeCherney, A.H. & Nathan, L. (2002). Current
Obstetrics and Gynaecology (9th Ed.). McGraw Hill.
•Hanretty, K.P. (2003). Obstetrics Illustrated (6th Ed.).
London: Churchill Livingstone.
•Oats, J., Abraham, S. (2005) Llewellyn-Jones
Fundamentals of Obstetrics and Gynaecology. (8th
Ed.). Edinburgh: Mosby.
•Parisaei, M., Shailendra, A., Dutta, R., Broadbent,
J.A. (2008). Crash Course: Obstetrics and
Gynaecology. (2nd Ed.) Mosby.