The document outlines the extensive physiological, anatomical, and biochemical changes that occur during pregnancy, affecting various body systems including the reproductive, cardiovascular, respiratory, urinary, endocrine, and musculoskeletal systems. Key hormonal changes mediate these adaptations, with progesterone, estrogen, and relaxin playing crucial roles in alterations such as increased blood volume, changes in body weight, and modifications in the renal and digestive systems. The document also emphasizes how these changes manifest as specific symptoms and physical adjustments, highlighting the overall complexity of adaptations to support fetal development.

1. PHYSIOLOGICAL
CHANGES DURING
PREGNANCY

2. During pregnancy there is progressive anatomical
physiological, biochemical change not only
confined to genital organs but also to all other
systems of the body.
• Reproductive system
• Cardiovascular system
• Respiratory system
• Urinary system
• Breasts
• Weight gain
• Endocrine system
• Nervous system
• Digestive system
• Musculoskeletal
system
• Skin

3. INTRODUCTION
The changes of pregnancy are the direct result of the
interaction of 4 factors.
1. Hormonally mediated changes in the collagen and
involuntary muscle.
2. Increased total blood volume with increased blood flow
to the uterus and kidneys.
3. Growth of fetus enlargement and displacement of
uterus.

4. ENDOCRINE SYSTEM
• Changes of pregnancy are orchestrated by hormones and
their action.
• Progesterone, oestrogens and relaxin are the important
hormones.

5. • Progesterone is produced first by corpus luteum, then
by placenta.
• Output of corpus luteum reach maximum of 30 mg/24 hrs at
about 10 weeks and then declines.
• Placenta begins increasing production from 10 weeks.
• The amount produced rises from 75mg/24 hrs at 20 weeks
to 250-300mg/24 hrs at 40 weeks.

6. • Oesterogen is produced first by corpus
luteum, then by placenta.
• Output of about 5mg/24 hrs at 20 weeks and
50mg/24 hrs at 40 weeks.
• Relaxin is thought to be synthesized in the
corpus luteum and later in the decidua.
• It is produced as early as 2 weeks of
gestation, it is at highest level in the 1st
trimester and then drops by 20% to remain
steady till delivery

7. • Effect of progesterone
1. Reduction in tone of smooth muscle:
food may stay longer in stomach, nausea,
peristaltic activity reduced, increased water
absorption in colon, constipation, uterine
tone reduced, bladder tone reduced.
2. Increase in temperature
3. Reduction in alveolar & arterial Pco2
tension, hyperventilation.
4. Development of breasts, alveolar and
glandular milk producing cells.

8. • Effect of Oestrogens
1. Increase in growth of uterus and breast ducts.
2. Increasing level of prolactin to prepare breasts for
lactation.
3. Increased water retention, may cause sodium to be
retained.

9. • Effect of Relaxin
1. Gradual replacement of collagen in target
tissues with a remodelled modified form that
has greater extensibility and pliability.
2. Role in mammary growth
3. May have a role in cervical ripening

11. REPRODUCTIVE SYSTEM
• Amenorrhoea is first sign of pregnancy.
• Within few days of conception the color of the cervix will
change from pink to bluish shade.
• Cervix in the final weeks involves changes like- softening,
greater distensibiity and dilatation of cervix.
• Growing uterus rises out of pelvis to become an
abdominal organ at about 12 weeks of gestation
displaces the intestines

12. • In the final 2-3 weeks the fetal head comes in pelvic inlet.
The uterus increases in size.
• The weight of the uterine tissue increases from 50-1000g
at term.
• Increase in elasticity by hormonal influence.
• Isthmus develops to become the lower uterine segment.
• Muscle fibres of the uterus increase in activity and
coordinated contraction of the uterus, detected by 20
weeks of gestation.

13. • Bursts of irregular, short, usually painless
contractions become evident and systematic.
These are called Braxton Hicks
contractions.
• At some stage regular and increasingly painful
contractions establish and labour is said to
begin.
• The fetal heart can be heard using sonic- aid
from about 14 weeks and by stethoscope at
about 24-26 weeks.
• Fetal movement felt by multigravida between
16-18 weeks and by primigravida between 18-
20 weeks.

15. CARDIOVASCULAR SYSTEM
Blood volume increases by 40% or more to
cope up with increasing requirements of
uterine wall, placenta.
Increase in plasma than in red cells, hence
hemoglobin level falls by 80%.
Called physiological anemia, this causes
tiredness and malaise from early pregnancy

16. • Progestrone acts on smooth muscle of vessel wall to
produce hypotonia and cause rise in temperature.
Pregnant women have a good peripheral circulation
hence they don’t feel cold.
• Heart increase in size increase in stroke volume &
cardiac output by 30-50%. Small increase in heart rate.
• In 2nd trimester, little fall in BP. Hence fainting can occur.

17. • In 3rd trimester, wt of fetus may compress aorta & inferior
vena cava against lumbar spine in supine position.
• Dizziness and unconsciousness
• Pregnancy hypotensive syndrome
• Exercise in heat should be avoided as there are chances
of teratogenic effect of raised core temp in early weeks.

18. • Reasons for varicose veins and gravitational oedema are-
1. Vascular hypotonia
2. Downward pressure of the enlarging uterus
3. Weight gain
4. Raised intra-abdominal pressure
5. Progestrone and relaxin mediated changes in collagen
• Varicosites of vulva and anus (haemorrhoids,piles) may
occur.

19. • Oestrogens are responsible for fluid retention in body
tissue
• Shape of the eye changes.
• Increased peripheral circulation and hormonal stimulation,
mucous membranes (eg. Nasal, vaginal) become more
active n lush snuffy nose and increase vaginal
discharge.

20. RESPIRATORY SYSTEM
• Resting respiratory rate - from 15 to 18 bpm
• Tidal volume - upto 40%
• Alveolar ventilation –
• Expiratory reserve volume –
• In 3rd trimester because of enlarging uterus the diaphragm
descents, by the term it displaces the diaphragm upward
by 4cm or more.

21. • Upward pressure of fetus causes flaring of ribs
• Subcostal angle increased by 10-15 cm.
• Relaxin softens costochondral junction and makes them
mobile

22. BREASTS
• By 3-4 weeks, enlargement begins. Stimulated by rising
level of oestrogens, progesterone and relaxin.
• Increases in Breasts weight in pregnancy is around 500-
800g.
• Sebum secreted assists the nipple to become more softer
and pliable.
• By 12th week pigmentation starts.

23. • Pigmentation is d/t stimulation of melanin production by
anterior pituitary.
• By 16th week colostrum can be expressed.
• Human milk ‘comes in’ about 3rd or 4th postpartum day.

24. SKIN
• Pigmentation is seen in linea alba, vulva and face.
• Stretch marks developed over buttocks, abdomen and
breast
• Increase in blood flow to the skin which increases the
activity of sebaceous and sweat glands
• Females are expected to drink more to compensate
• Fat is laid on thighs, upper arms, abdomen & buttocks

26. URINARY SYSTEM
• Increased blood supply to kidney and urinary tract
• Increase in size of kidney by 1cm & Dilation of ureter , renal pelvis.
• In later pregnancy , uterus compresses the ureters at the pelvis brim ,
causing slowing of urine flow.
• Increases in urine output, small changes in tubular
• resorption .
• Increases frequency of micturition is noticed at 6-8 weeks of
pregnancy, which subsides after 12weeks .
• Stress incontinence may occur due to urethral sphinter weakness.

27. DIGESTIVE SYSTEM
 Nausea, vomiting occur most commonly in early
pregnancy.
 Muscle tone and motility of entire GI tract decrease due to
high progesterone level.
 Decreased gastric secretions, increased gastric emptying
time.
 Increased relaxation of smooth muscle and water
absorption in colon leads to constipation.

28. NERVOUS SYSTEM
 Anxiety , increased mood lability , vivid nightmares, food
fads and insomnia are common.
 More prone to compression of distal nerves because of
increase in fluid. Eg. Carpal Tunnel Syndrome.

29. BODY WEIGHT GAIN
• Weight gain in first 20 weeks of pregnancy is small (0-
2)kg.
• It then increases to 1.0 kg/month to 30 weeks , then
increasing to 1.0kg/fortnight between 30 and 40 weeks.

31.  The total weight gain during the course of pregnancy for
woman averages 10-12 kg.
 Weight distribution :
Breasts : 0.5 kg
Foetus : 3.3 kg
Blood volume : 1.2 kg
Placenta : 0.6 kg
Amniotic fluid : 0.8 kg
Uterus : 0.9 kg
Fat deposits : 4.0 kg
Extracellular fluid : 1.2 kg

32. MUSCULOSKELETAL SYSTEM
• Generalized increase in joint laxity .
• The muscles of abdominal wall adapt to increasing foetal growth
with stretching of muscle fibres.
• Maternal COG shifts posteriorly to accommodate the increase
in abdominal size. this reduces stability & may results in
‘waddling gait’ .
• Women usually walks with wider base of support.
• Back pain is a common symptom in pregnancy.

33. • Thoracic and lumbar curves increase.
• Upper back become rounded , with scapular protraction ,
tightness of pectoralis muscles and scapular muscle
weakness
• Cervical lordosis increased which leads to forward head
posture.
• Many women experience painful muscle cramps during
pregnancy , mainly in lower limbs.

35. REFERENCES
Physiotherapy in Obstetrics and Gynecology- Margaret
Polden, Jill Mantle pg-26-40