Physiologic changes in pregnancy, in obstetric practice

1. Physiologic
changes of
pregnancy
Lando Elvis Otieno

2. Jens
Martensson
2
.
.
OUTLINE
Definition
Normal changes
-CV
-Respiratory
-Hematologic
-Endocrine
-Urinary
-GI
-Reproductive organs
-Skin
-Musculoskeletal
Implications for pathological conditions.
Pregnancy as a “stress test for life”
Unveils problems that will appear later.

3. Jens
Martensson
.
THE CHANGES THAT TAKE PLACE IN
THE MATERNAL ORGAN SYSTEM IN
RESPONSE TO PREGNANCY.
TO ACCOMADATE THE PREGNANCY
AND TO PREPARE THE WOMAN FOR
LABOUR
Definition
3

4. Jens
Martensson
4
Metabolic and
endocrine
changes
HORMONES
OESTROGEN
• Produced in corpus luteum
• Produced by placenta after 12 weeks
• Responsible for growth particularly of
uterus and breasts
• PROGESTERONE
• Produced in corpus luteum and then the
placenta
• Relaxes smooth muscle
• Inhibits uterine contractions until uterus
is prepared for labour
• Regulates storage of body fat

5. Jens
Martensson
HUMAN CHORIONIC GONADOTROPHIC
• RELAXIN
5
HORMONES cont.
• Secreted from trophoblast of the
developing embryo
• Maintains corpus luteum until placenta
takes over
• Used in tests to confirm pregnancy
• HUMAN PLACENTAL LACTOGEN
• Alters maternal metabolism
• Diverts glucose to fetus
• Mobilises free fatty acids from maternal
stores
• Released by corpus luteum then the
Placenta
• Softens pelvic ligaments
• Reduces myometrial tone
• Relaxin peaks in early and late
pregnancy. Women with chronic joint
instability may notice an increase in
symptoms during these times.

6. Jens
Martensson
• NOTE
• Edema is present in the
hands. feet. face and
eyelids. This is due in
part to sodium and water
retention. Additionally.
hormones circulating by
the placenta. ovaries,
and adrenal cortex
cause increased
capillary permeability,
which contributes to the
edema many pregnant
women experience.
6
Metabolic and endocrine changes
cont...
Endocrine (insulin) changes:
-Pregnancy is diabetogenic due to placental
hormones (Placental lactogen, HGH, cortisol,
progesterone).
-Insulin requirement increases during
pregnancy.
-Insulin requirement falls abruptly after
delivery.
• Anti-insulin environment is aided by:
• placental lactogen
• Like growth hormone
• Increases lipolysis and FFA
• Increases tissue resistance to insulin
• Increased unbound cortisol

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Martensson
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Metabolic and endocrine changes
cont...
• BMR increases by 20-25 % during pregnancy
• Recommended weight gain – 25-35 lb
• Overweight – 15-25 lb
• Underweight – 25-35 lb
• Need for increased iron, calcium, fat, and protein
• Caloric requirements increases by ~ 300 calories/day
• Increase in Protein and fluid requirements
.
METABOLISM

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Martensson
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Metabolic and endocrine changes
cont...
• Estrogen stimulates Increase in TBG
• Total T3 and T4 are increased
• However the active hormones remains
unchanged
• hCG stimulates thyroid
• TSH is reduced
• Iodine deficient state
• Due to Increased renal clearance
• To rule out pathologic changes
• Early in pregnancy TSH can be used
• Later free T4 is needed
LIVER
• Liver morphology unchanged
• Lab Tests similar to liver disease
• Alkaline phosphatase doubles
• AST, ALT, GGT and bilirubin are slightly lower
• Decreased plasma albumin
• GALBLADER
• Impaired contraction. . High residual volumes
• Promotion of stasis
• Stasis associated with increased cholesterol
saturation of pregnancy, supports predisposition
of stones
• Intrahepatic cholestasis
THYROID

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Martensson
CARDIOVASCULAR CHANGES
9
Growth
Shows
Sales
To meet increased metabolic demand.
-Increased blood volume(50%) / RBC mass
-Reversible cardiac hypertrophy (30%?)
-Decreased Hct and viscosity
-increase in SV(25 – 30%)
-increase in cardiac output
-increase in HR at given work load
-increase in blood volume (mostly during latter half of pregnancy)
-Uterus may compress large blood vessels reducing venous return

10. Jens
Martensson
Cardiovascular Changes
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DECREASE
-Hematocrit
-Blood pressure
-Blood supply to
uterus
-Cardiac reserve
-Vascular resistance
Heart shifts up and to the left
Hemoglobin stays the same (12-
16 g/dL) initially
May drop down to 10 g/dL and
still be normal physiologic
anemia.
Normal pregnancy Hgb is 10-
14 g/dL later in pregnancy
Decreased Hct (38-47%)
Normal pregnancy Hct is 32-42
later in pregnancy
Pulse rate may increase 10-15
beats.
Weight of uterus can cause supine
hypotensive syndrome.
INCREASE
-Blood volume
-Cardiac (heart) output
-Stroke volume
-End diastolic volume
-Resting pulse
-% of blood plasma

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Martensson
Supine hypotension related to
Venal cava syndrome
11
This leads to dizziness,
air hunger, nausea
2.5 3.5

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Martensson
Total body water
12
-Increases 6-8 L
-Increases by 40 %
-Normal body water
2/3 intracellular
1/3 extracellular
¾ interstitial
¼ intravasular
-2/3 increase is extravascular

13. Physiologic anemia of pregnancy
Physiologic intravascular change
Plasma volume increases 50-70 %
Beginning by the 6th wk
RBC mass increases 20-35 %
Beginning by the 12th wk
Disproportionate increase in plasma volume over RBC volume----
Hemodilution
Despite erythrocyte production there is a physiologic fall in the
hemoglobin and hematocrit readings

14. Jens
Martensson
Cont…
• With erythropoiesis of pregnancy,
iron requirements increase.
• Because large amounts of iron may
not be available from body stores
and may not be in the diet
• Supplementation is recommended
to prevent iron deficiency anemia
• At term, Hemoglobin less than 10.0
is usually due to iron deficiency
anemia rather than the
hemodilution of pregnancy
Normal Iron Requirements
• Total body iron content average in normal
adult females is 2gm
• Iron requirement for normal pregnancy is
1 gm
• 200 mg is excreted
• 300 mg is transferred to fetus
• 500 mg is need for mom
• Total volume of RBC inc is 450 ml
• 1 ml of RBCs contains 1.1 mg of iron
• 450 ml X 1.1 mg/ml = 500 mg
• Daily average is 6-7 mg/day
• Small intervals between pregnancies are
most concerning
Iron deficiency anemia

15. Jens
Martensson
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RESPIRATORY SYSTEM CHANGES
• Mechanical
• diaphragm
• Consumption
• Increase in needed oxygen
• Stimulation
• Progesterone stimulation
Respiratory Changes
Respiratory Changes

 Respiratory capacity
Respiratory capacity
increases
increases

 Shortness of breath
Shortness of breath

 Pulmonary reserve
Pulmonary reserve
decreases
decreases

 Increased risk of
Increased risk of
muscle soreness
muscle soreness

 Tendency to
Tendency to
hyperventilate
hyperventilate
RESULT
RESULT adjust the intensity level and duration of exercise
adjust the intensity level and duration of exercise

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Martensson
• increase respiratory rate
• increased oxygen consumption
• common are nasal stuffiness,
nosebleeds due to Increased
vascular swelling to nose
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RESPIRATORY SYSTEM CHANGES cont…
• Consumption
• O2 consumption Increases 15-20
%
• 50 % of this increase is required
by the uterus
• Despite increase in oxygen
requirements, with the increase
in Cardiac Output and increase in
alveolar ventilation oxygen
consumption exceeds the
requirements.
• Therefore, arteriovenous oxygen
difference falls and arterial PCO2
falls.

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Martensson
• Displacement of the stomach and
intestines
• Appendix can be displaced to
reach the right flank
• Gastric emptying and intestinal
transit times are delayed secondary
to hormonal and mechanical
factors
• Pyrosis is common due to the
reflux of secretions
• Vascular swelling of the gums
• Hemorrhoids due to elevated
pressure in veins
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PHYSIOLOGIC CHANGES IN
GASTROINTESTINAL
• Digestive system slow due to
progesterone
• Nausea and vomiting(hyperemesis)
• Ptyalism: increase salivation
• Heartburn
• Hemorrhoids
• Prolonged gallbladder emptying
time may lead to gall stones
• Bile salt buildup may lead to
itching.

18. Jens
Martensson
• Uterus –
• Enlarges : esp fundal area thickens, then thins
later in preg
• Umbilicus by 20 weeks
• Xyphoid by 36 weeks fundus, Braxton-Hicks
irregular contractions after 4 months
• Cervix – mucous plug, Goodell’s sign, Chadwick’s
sign.
• Length remains the same
• Increase in width
• Softening after third month due to oestrogen
• Increased vascularity
• Increased cervical mucosa
• Increased glandular function
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Physiologic changes in pregnancy -
Reproductive system
• GENITAL TRACT
• Increased vascularity and hyperemia
• Vagina
• Perineum
• Vulva
• Increased secretions
• Characteristic violet color of the vagina
• Chadwick’s sign
• Increased length to the vaginal wall
• Hypertrophy of the papillae of the vaginal
mucosa

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Martensson
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Relative Uterus Size During Pregnancy
• uterus grows to 30x23x20 at term
weight increases to 900gms
• hypertrophy.. Oestrogen causes
cells to increase until 20 weeks
gestation
• Hyperplasia:- number of cells
increase under the influence of
oestrogen
• After 20 weeks of gestation: Uterine
muscle tissue stretches to allow fetus to
grow, and Progesterone relaxes the
smooth muscles enabling it to stretch

20. Jens
Martensson
• By 2ND TRIMESTER
• Development of the upper and lower uterine
segment
• Upper segment, thicker containing oblique
muscles
• Lower segment formed from the isthmus
contains circular and longitudinal muscles
• Uterus is pear shaped again
• Braxton Hicks contractions
• BY 3RD TRIMESTER
• Lower segment formed from isthmus and
contains longitudinal fibres .Upper segment
thick and contains oblique muscle fibres
• By 36 weeks lower segment measures 8-10cms
• Engagement
• By 38 weeks the cervix is taken up into the
20
Changes in the shape of the
uterus
• Isthmus elongates during the 1st 10
weeks like a stalk
• From 7mm to 2.5cms at 10 weeks
• Later becomes the lower segment with
the globular uterus sitting on top
• By 12 weeks
• Uterus is upright and leans slightly to
the right
• No longer a pelvic organ
• Uterus may be palpable above the pubic
bone
• Fetus now occupies most of the uterine
cavity
• Placenta now developed

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Martensson
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BLOOD SUPPLY TO UTERUS CHANGES
• Blood supply pre pregnancy =
10mls/min
• At 40weeks 800 – 900mls/min
• 20% of cardiac output goes to uterus

22. Jens
Martensson
• PHYSIOLOGIC CHANGES
• Urinary tract changes result form the inc
blood volume and glom filtration rate and
inc fundal size puts pressure on internal
organs
• More susceptible to infection dt dec blood
flow and traumaGFR raises by 50%
• Increased renal clearance leads to lowered
BUN and nonprotein nitrogen values.
• Renal plasma blood flow increases 50%
• Glomerular Filtration Rate increases
• Bicarbonate increased excretion
• Creatinine increased excretion
• Renal pelves and ureters dilate
• Smooth muscle of bladder relaxes/stasis
• Sugar may spill at 160/protein PIH
22
RENAL SYSTEM
• Dilation of the renal vessels
• Due the effects of progesterone
• Increased renal blood flow
• Gfr increases by 60% in early pregnancy
• Size of pores increased
• URINARY CHANGES
• Kidneys grow and filter more blood
as the blood volume increases
• Become more susceptible to
bladder and kidney infections
• Bladder becomes compressed
causing frequent urination and

23. Jens
Martensson
Pigmentation: It is due to suprarenal
changes, it usually begins to appear after
the 4th month. The pigmentation may
appear anywhere but the commonest sites
are:
1. Linea nigra: which is a line of
pigmentation between the umbilicus and
the
symphysis pubis.
2. Increased pigmentation of the nipple as
primary areola and appearance of the
secondary areola.
• MOST OF THESE RESOLVE AFTER
PREGNANCY 23
Integumentary system physiologic
changes
Due to overstretching of the skin, the
elastic fiber may rupture together with
small blood vessels and so red streaks
appear; known as striae gravidarum.
They are usually more marked below
the umbilicus, on the breasts and may
appear on the buttocks and thighs. In
some women they are not marked or
even don't
appear during pregnancy. After labour,
the red striae become pale silvery white
due to fibrosis and are known as (striae
albicantes).

24. Jens
Martensson
• Stria gravidarum
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Integumentary system physiologic changes…cont
• Linea nigra

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Martensson
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Integumentary system physiologic changes…cont
3. Cloasma gravidarum/ Melasma or
mask face of pregnancy which is
butterfly
pigmentation of the forehead, nose, upper
lip and the adjoining parts of the
checks. This pigmentation may persist but
the cloasma gravidarum usually
disappears.
Falling of hairs and brittleness of nails may
occur during pregnancy.

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Martensson
26
Breast Changes
-Early in pregnancy, tenderness and
tightness is common
-After 8 weeks, breasts grow and
blood vessels often are visible
-Nipples become larger and darker
-A thick yellowish fluid can be
expressed from the nipple

27. Jens
Martensson
Postural changes:
During pregnancy, postural changes
occur to accommodate for abdominal
growth.
a. These changes include forward head,
rounded shoulders, increased lumbar
lordosis, hyperextended knees, and
pronated feet.
b. The center of gravity changes,
resulting in changes in balance.
c. Muscular changes are also typical.
often noted alterations include
shortened hip flexors, lower back
musculature, and pectorals.
Abdominal muscles, neck, and upper
back muscle groups elongate. This
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Musculoskeletal system changes
• Diastasis recti: separation of rectus
abdominous : Abdominal muscles are
stretched to the point of their elastic limit by
the end of pregnancy.
• Hormonal influence on the ligaments is
profound producing systemic decrease in
ligamentous tensile strength and an increase
in mobility of structures supported by
ligaments and may predispose the patient to
joint injury especially in the weight-bearing
joints of the back, pelvis and lower
extremities. The pelvic floor muscles must
withstand the weight of the uterus, the floor
drops as much as 2.5 cm.
Bones and joints:There is tendency to
decalcification of bones, sublaxation of joints
due to softening of ligaments by relaxin
hormone. It is more marked in sacroiliac joint

28. Jens
Martensson
• Brain adaptations
• Not really understood (progesterone
metabolites on GABA pathways?), but
the neuroendocrine response to stress is
reduced in pregnancy.
• Pituitary increases in size during
pregnancy
• Due to increased prolactin and ACTH
secretion from AP
• And increased oxytocin production from PP
(where it is stored until progesterone levels
drop)
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Neurological and sensory Changes
• Decreased intraoccular pressure
• Corneal thickening
• Altered sense of smell
• Decreased attention span
• Problems with memory
• Altered CNS physiology leading to
mood disturbance.

29. Jens
Martensson
SUMMARY
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In summary, pregnancy alters the body from head to toe. The effects of these changes
vary as the pregnancy progresses through the trimesters.
In the first trimester, the baby begins to grow and the mother experiences increased
urination, changes in skin and hair, and a thickening waistline. Changes in the
cardiovascular system and metabolism can cause nausea and fatigue.
In the second trimester, the baby's weight increases from an ounce to more than a pound.
The pregnant soldier’s energy level improves, but she may experience heartburn, leg
cramps, and her pelvis may relax causing discomfort to her sacro-iliac joint.
During the third trimester, the baby has more rapid growth and weight gain. The pregnant
soldier may have backaches, swelling of the hands, legs, and feet, and may feel warmer.
She may experience breathlessness and more frequent urination as additional weight is
placed on the bladder. Most changes that occur will be normal and will go away after
delivery.

30. .

31. Jens
Martensson
• 1.Current diagnosis & treatment obstetrics & gynecology, 12th edition: By alan H.
Decherney (author), lauren nathan (author), T. Murphy goodwin (author), neri laufer (author), ashley S.
Roman (author)
• 2.Obstetrics & Gynaecology Ten Teachers 19th Edition
• by Philip N. Baker (Editor), Louise Kenny (Editor), Ash Monga (Editor), Stephen Dobbs (Editor)
• 3.Internate:
• Physiological changes of pregnancy
https://medschool.ucsd.edu/som/.../Physiological%20changes%20of%20pregnancy.pp
• Physiologic Changes in Pregnancy - UNC School of Medicine
www.med.unc.edu/obgclerk/resources/repro-med.../PhysiologicChanges_2009.ppt
• Physiological changes in pregnancy-site.iugaza.edu.ps/abahri/files/2010/.../ch-14-Physiological-
changes-in-pregnancy1.pp...
REFERENCE

32. L.E.O
Lando.elvis@students.ac.ku.k
e
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