The document discusses the physical and physiological changes that occur during pregnancy. It covers changes to various body systems including: - Hormonal changes mediated by progesterone, estrogen, and relaxin which impact collagen, smooth muscle tone, blood volume, and more. - Growth of the uterus displacing organs and increasing blood flow to support the fetus. - Impacts to respiratory, cardiovascular, gastrointestinal, skin and breast tissue to accommodate the needs of pregnancy and fetal growth. - Descriptions of cervical changes, Braxton Hicks contractions, and impacts of the growing fetus on organs like the diaphragm.

1. The Physical And Physiological
Changes Of Pregnancy
DR.HAFSA IMTIAZ (DPT)

2. THE PHYSICAL AND PHYSIOLOGICAL
CHANGES OF PREGNANCY
• The changes of pregnancy are chiefly the direct
result of the interaction of four factors:
1. the hormonally mediated changes in collagen and
involuntary muscle
2. the increased total blood volume with increased
blood flow to the uterus and the kidneys
3. the growth of the foetus resulting in consequent
enlargement and displacement of the uterus
4. the increase in body weight and adaptive changes in
the centre of gravity and posture
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3. Endocrine System
• The changes of pregnancy are orchestrated by
hormones:
1. Progestrone
2. Estrogen
3. Relaxin.
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4. Progestrone.
• Progesterone is produced first by the corpus
luteum reaches a maximum of about 30mg per
24 hours at about 10 weeks of pregnancy and
thereafter declines,
• then by the placenta, increasing production from
about 10 weeks, which at first supplements that
from the corpus luteum and then completely
takes over the role.
• Three progestogens are produced in the placenta
but the chief one is progesterone.
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5. ROLE OF PROGESTRONE
1. Reduction in tone of smooth muscle:
(a) food may stay longer in the stomach; peristaltic activity is
reduced
(b) water absorption in the colon is increased leading to tendency
to constipation
(c) uterine muscle tone is reduced; uterine activity is damped
down
(d) detrusor muscle tone reduced
(e) dilatation of the ureters favouring urine stasis with elongation
to accommodate the increasing size of the uterus; this may
contribute to the likelihood of urinary tract infections
(f) urethral tone reduced, which may result in stress incontinence
(g) reduced tone in the smooth muscle of the blood vessel walls
leading to dilation of blood vessels, lowered diastolic
pressure.Hafsa Imtiaz
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6. CONT…..
• 2. Increase in temperature (0.5–1°C).
• 3. Reduction in alveolar and arterial PCO2
tension, hyperventilation
• 4. Development of the breasts’ alveolar and
glandular milk-producing cells.
• 5. Increased storage of fat.
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7. ESTROGEN
• Oestrogens are produced first by the corpus
luteum and then by placenta
• Several estrogens are produced by placenta but
oestriol produced in excessive quantities and
excreted in maternal urine and amount of it
excretion indicates well being of fetus.
• foetal adrenal glands and the foetal liver also
contribute towards oestrogen synthesis in
pregnancy
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8. Effects Of Estrogen
• Increase in growth of uterus and breast ducts.
• Increasing levels of prolactin to prepare breasts
for lactation; oestrogens may assist maternal
calcium metabolism.
• May prime receptor sites for relaxin (e.g. pelvic
joints, joint capsules, cervix).
• Increased water retention, may cause sodium to
be retained.
• Higher levels result in increased vaginal
glycogen, predisposing to thrush.
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9. Relaxin
• Relaxin is produced in the theca and luteinised
granulosa cells in the corpus luteum and later in
decidua.
• relaxin might have a role relating to continence
in pregnancy.
• Research suggests that it is produced as early as
2 weeks of gestation
• It is at highest levels in the first trimester, and
then drops by 20% to remain steady
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10. Effects Of Relaxin
• Gradual replacement of collagen in target tissues (e.g.
pelvic joints, joint capsules, cervix) with a remodelled
modified form that has greater extensibility and pliability.
Collagen synthesis is greater than collagen degradation and
there is increased water content, so there is an increase in
volume.
• Inhibition of myometrial activity during pregnancy up to 28
weeks when women become aware of Braxton Hicks
contractions.
• May have a role in the remarkable ability of the uterus to
distend and in the production of the necessary additional
supportive connective tissue for the growing muscle fibres.
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11. Cont….
• Rising levels of relaxin effect softening of the
collagenous content of the cervix Towards the
end of pregnancy.
• May have a role in mammary growth.
• Affects relaxation of the pelvic floor muscles
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12. Reproductive system changes
• Amenorrhoea is one of the first signs of
pregnancy for most women.
• Other changes include:
• Cervical
• Uterine
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13. Cervical Changes
• Cervix will be seen to have changed in colour from pink to a
bluish shade.
• Cervix first increase in depth,
• In late pregnancy ripening of cervix occur, involves the
softening, greater distensibility, effacement and eventually
dilation of the cervix
• are produced by the endocrine-controlled restructuring of
collagen and other tissues
• As pregnancy progresses a plug of thick mucus forms in the
cervical canal, sealing the uterus
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14. Bishop’s score
• The Bishop Score (also known as Pelvic Score) is the
most commonly used method to rate the readiness of
the cervix for induction of labor.
• The Bishop Score gives points to 5 measurements of
the pelvic examination
• dilation,
• effacement of the cervix,
• station of the fetus,
• consistency of the cervix, and
• position of the cervix
• If the Bishop score is 8 or greater the chances of
having a vaginal delivery are good and the cervix is
said to be favorable or "ripe" for induction.
• If the Bishop score is 6 or less the chances of having
a vaginal delivery are low and the cervix is said to
be unfavorable or "unripe" for induction.
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15. Hafsa Imtiaz
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16. UTERINE CHANGES
• The growing uterus rises out of the pelvis to
become an abdominal organ at about 12 weeks’
gestation
• displacing the intestines and coming to be in
direct contact with the abdominal wall as
pregnancy proceeds.
• in the final 2–3 weeks the fundal height drops
particularly noticed by the primigravida.
• because the foetal head has entered
the pelvic inlet
• which may cause an increased frequency of
micturition
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17. CONT……
• head will be said to be ‘engaged’ when its
greatest diameter has passed through the brim of
the pelvis
• At the end of pregnancy abdominal palpation is
used to determine how much of the foetal head
remains above the pelvic brim
• This is estimated in fifths or by using the terms
‘unengaged’, ‘engaging’, ‘engaged’
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18. CONT…….
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19. CONT……
• With increase In uterus size, blood supply also
increases.
• The weight of the uterine tissue itself increases
from about 50g to 1000g at term
• The collagenous tissue increases in area and
elasticity through pregnancy under hormonal
influence.
• The muscle fibres of the fundus and body
increase in length and thickness throughout
pregnancy to accommodate the growing foetus.
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20. CONT……
• As pregnancy progresses the isthmus develops to
become the lower uterine segment
• by term it accounts for approximately the lower
10cm of the uterus above the cervix.
• musculature is not highly developed in this area
and towards term it becomes soft and stretchy,
allowing the foetus to sink lower in the uterus
and into the true pelvi
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21. Braxton Hicks Contraction
• Braxton Hicks contractions are painless sporadic contractions
and relaxation of the uterine muscle. Sometimes, they are
referred to as prodromal or “false labor" pains.
• Occur because Uterine muscle fibres activity increases and
coordinated contractions occur by 20th week of gestation.
• they facilitate the blood flow through the placental site and
play a part in the development of the lower uterine segment
• Braxton Hicks contractions are thought to play a role in toning
the uterine muscle in preparation for the birth process.
• Occur when fetus is stressed and need increased blood flow to
placenta to provide fetal oxygenation,
• triggers may include, when the woman is very active, when the
bladder is full, following sexual activity, and when the woman is
dehydrated.
• some women experience considerable sequences of
contractions of variable length 20 seconds to 4 minutes. Hafsa Imtiaz
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22. Cardiovascular system
• Blood volume increases by 40% or more to cope
with:
• increasing requirements of the uterine wall with the
placenta
• weight gain
• supplying the greater bulk
• increased power needed to move it
• DILUTION ANAEMIA
• Also known as physiological anemia of pregnancy
• Plasma concentration increses and consequentaly
hemoglobin level falls to about 80%
• One of the cause of tierdness and malaise experienced
by women in early pregnancy Hafsa Imtiaz
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23. CONT…….
• Progesterone acts on the smooth muscle of blood
vessel walls to
• produce slight hypotonia, and
• causes a small rise in body temperature;
• therefore pregnant women generally have a good
peripheral circulation and do not feel the cold.
• The heart size increases and accommodate more
blood so:
• stroke volume rises
• cardiac output increases by 30–50%
• there is a progressive small increase in heart rate
through pregnancy Hafsa Imtiaz
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24. CONT……
• Blood pressure may even fall a little through the
second trimester of pregnancy, so women may
easily feel faint from prolonged standing
• pregnancy hypotensive syndrome:
• In the third trimester the weight of the foetus may
compress the aorta and inferior vena cava against the
lumbar spine when the woman is lying supine, causing
dizziness and even unconsciousness
• varicose veins particularly in the legs and
gravitational oedema occur due to:
• Slight vascular hypotonia, downward pressure of the
enlarging uterus, weight gain, raised intra-abdominal
pressure, and progesterone and relaxin-mediated changes
in collagen Hafsa Imtiaz
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25. CONT….
• Varicosities of the vulva and anus (haemorrhoids,
piles) may also occur.
• Oestrogens may be responsible for fluid retention
in body tissues.
• Some women can no longer wear hard contact
lenses because their eye shape changes
• symptoms such stuffy’ nose and increased vaginal
discharge can be observed
• As a result of the increased peripheral circulation and
hormonal stimulation, the mucous membranes (e.g.
nasal, vaginal) become more active and lush
• Consequently prolongation of coughs and colds may be
experienced, also nose bleeds and vaginal thrush
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26. Respiratory system
EFFECTS ON VENTILATION
• Slight increase in ventilation occur due to:
• increased circulating progesterone levels in pregnancy
further sensitise the respiratory centre in the medulla
to carbon dioxide
• increasing demand for oxygen
• resting respiratory rate goes up a little, from
about 15 to about 18 breaths per minute, and
there is a lowering by some 2% of the maternal
blood carbon dioxide tension
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27. Cont….
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EFFECTS ON VOLUMESAND CAPACITIES
• Tidal volume increases gradually by up to 40%, and alveolar
ventilation also rises
• Vital capacity remains same while expiratory reserve
reduces
EFFECTS ON DIAPHRAGM:
• By the third trimester, enlarging uterus increasingly
impedes the descent of diaphgram
• Towards term it may actually displace the diaphragm
upwards, often by 4cm or more
• where the foetus is large or
• the abdominal component of the maternal torso is short,
• or both

28. CONT…
• ON RIBS CAGE
• The upward pressure of the foetus causes rib flaring
• Maternal lower costal girth is increased, often by as
much as 115cm, as is the subcostal angle
• Because of this the respiratory excursion is limited at
the lung bases and greater movement is observed in
the mid-costal and apical regions
• women frequently experience considerable
breathlessness on even modest exertion towards the
end of the pregnancy.
• hormone relaxin softens the costochondral junctions
and renders them more mobile
• Women complain of costal margin pain or rib ache, and
of the foetus kicking the diaphragm and ribs Hafsa Imtiaz
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29. Breast
• As early as 2–4 weeks of pregnancy:
• unusual tenderness and tingling may be experienced in the breasts
• enlargement begins soon, with the breasts becoming nodular and
lumpy.
• The rise in oestrogens is responsible for the growth of the duct
system
• The rise in progesterone is responsible for growth of the alveoli
• total breast weight increases to about 400–800g
• blood supply increases
• number, size and complexity of the ducts increases
• At about 8 weeks, sebaceous glands in the pigmented area
around the nipples become enlarged and more active,
appearing as nodules
• The sebum secreted assists the nipple to become softer and more
pliable
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30. CONT…….
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• By 12 weeks of pregnancy the nipples and an
area around them become more pigmented due
to the stimulation of melanin production by the
anterior pituitary
• remain as for 12 months after parturition.
• In 12th week a little serous fluid may be
expressed from the nipples
• by about the 16th week colostrum can be
expressed.
• Human milk ‘comes in’ about the 3rd or 4th
postpartum day

31. SKIN
• darkening of the skin of the vulva, nipples and face
• chloasma’ or the ‘mask of pregnancy:
• blotches which sometimes occur on the forehead and cheeks
• pigmentation may also form a dark line in the skin
overlying the linea alba
• Striae or ‘stretch marks’ can develop over buttocks,
abdomen and breasts and may become pigmented
• There is an increase in blood flow to the skin, which
increases the activity of
• sebaceous and
• sweat glands, and so increases evaporation
• Fat is laid down, on the thighs, upper arms, abdomen
and buttocks, in the second and third trimesters, act
as:
• store which is subsequently called on in breastfeeding,
provided a woman does not ‘eat for two’ in the puerperium
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32. Gastrointestinal system
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• Nausea and vomiting, thought now to be the
response of some to HCG
• can be aggravated by certain foods, even by their
odours, and by iron tablets
• if inappropriately managed leads to Hyperemesis
gravidarum
• characterized by severe nausea, vomiting, weight loss,
and possibly dehydration. Feeling faint may also occur.
• gut musculature becomes slightly hypotonic and
the motility is decreased leading to:
• Prolong gastric emptying time
• slower passage of food

33. CONT….
• Delayed large bowl motility leads to:
• increased absorption of water and a consequent
predisposition to constipation because the faeces are dry
and hard
• Heart Burn or GERD occur due to:
• reduced speed of oesophageal peristalsis,
• hormonally mediated slackness of the cardiac sphincter,
• displacement of the stomach and
• an increased intra-abdominal pressure as pregnancy
progresses
• There is softening and hyperaemia of the gums and
bleeding may occur from minor trauma.
• Salivation may be increased.
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34. Nervous system
• Mood lability, anxiety, insomnia, nightmares, food
fads and aversions, slight reductions in cognitive
ability and amnesia are common in pregnancy.
• Water retention frequently causes unusual pressure
on nerves, particularly those passing through canals
formed of inelastic material like bone and fibrous
tissue (e.g. the carpal tunnel), with resulting
neuropraxia.
• Occasionally pregnant women complain of symptoms
indicating traction on nerves, which can be due to
increased weight, for example water retention in the
arm increasing its weight and producing depression of
the shoulder, and paraesthesia in the hand.
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35. Urinary System
• HCG hormone is present in urine early in pregnancy
• blood supply to the urinary tract in order to cope
with the additional demands of the foetus for waste
disposal
• increase in size and weight of the kidneys, and
dilation of the renal pelvis
• vesicoureteral reflux:
• The musculature of the ureters is slightly hypotonic so
that they are a little dilated, and also seem to elongate
to circumvent the enlarging uterus
• Leading to pooling and stagnation of urine; this may
predispose to urinary tract infections
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36. CONT….
• As the pregnancy progresses the bladder changes
position to become an intra-abdominal organ
• It is pressed upon and even displaced by the
increasingly large and heavy uterus
• urethrovesical angle may be altered and the intra-
abdominal pressure raised;
• the smooth muscle of the urethra may become
slightly hypotonic, and supportive fascia and
ligaments of the tract and pelvic floor may become
more lax and elastic leading to urinary frequency in
early pregnancy.
• Later in pregnancy there may be urge and stress
incontinence
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37. Musculoskeletal system
• There is a generalized increase in joint laxity leading to increased
joint range,
• which is hormonally mediated.
• Oestrogens, progesterone, endogenous cortisols and particularly relaxin
seem to be responsible for this.
• the laxity is made possible by a gradual breakdown of collagen in the target
tissue and its replacement with a remodelled modified form which has higher
water content and which has greater pliability and extensibility.
• During pregnancy it is usually necessary for a woman to adapt her
posture to compensate for her changing centre of gravity
• How a woman does this will be individual and will depend on many factors,
including
• muscle strength,
• joint range,
• fatigue and
• role models
• The changing centre of gravity is chiefly made necessary by the
distending abdomen
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38. CONT……
• the lumbar and thoracic curves are increased
• the greater lumbar lordosis was due to an increase in
the pelvic tilt
• about 50% of pregnant women experience back pain
• The increased body weight must result in more
pressure through the spine, and increased torsional
strains on joints. Women become clumsier and are
inclined to trip and fall. These factors, together with
joint laxity and fatigue (see p. 161), particularly in
the first and third trimester, must make pregnant
women more prone to injury
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39. Cont……
• abdominal wall adapts to the required degree of
distension
• The muscle fibres permit stretch, but the collagen components –
the aponeurosis, fibrous sheaths and intersections, and the linea
alba undergo hormonally mediated structural change to provide
the necessary temporary extra extensibility.
• Diastasis recti can occur, that is the partial or complete
separation of the rectus abdominis
• in the third trimester there is increased water retention,
which may result in a
• varying degree of oedema of ankles and feet reducing joint
range
• Edema cause pressure on nerves, as in carpal tunnel syndrome,
causes paraesthesia and muscle weakness affecting terminal
portions of the median and ulnar nerve distributions.
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40. Hafsa Imtiaz
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