maternal phy

1. MATERNAL
PHYSIOLOGY
PGI CHAUDHARY PRABIN
WVMC
DEPARTMENT OF OBGYN

38. Maternal
Physiology

39. Table of Contents
REPRODUCTIVE
TRACT & BREASTS
CARDIOVASCUL
AR SYSTEM
RESPIRATORY
TRACT
URINARY
SYSTEM
GASTROINTESTI
NAL TRACT
ENDOCRINOLOG
E SYSTEM
METABOLIC
CHANGES
HEMATOLOGIC
CHANGES
MUSCULOSKELE
TAL SYSTEM
SKIN
CENTRAL
NERVOUS
SYSTEM

40. 01
Reproductive Tract &
Breasts

41. Uterus
• Transformed into a thin-walled
muscular organ
• THICKER – first few months of
pregnancy
• 12th week of pregnancy - remains as
pelvic organ
• It displaces intestine and undergoes
DEXTROROTATION (rotation to the
right) caused by presence of
rectosigmoid colon on the left side
VOLUME 5 liters
WEIGHT
70 g - nonpregnant
1100 g - pregnancy
SHAPE
Shape: Piriform or pear shape🡪
Globular and almost spherical (12
weeks) 🡪 Ovoid
UTERINE
CONTRACTILIT
Y
Braxton hicks contractions🡪
intensity between 5-25 mmHg🡪
(near term) every 10-20 minutes
UTEROPLACE
NTAL BLOOD
FLOW
approx. 450 mL/min in the
midtrimester 🡪 500-750 mL/min at
36 weeks
Veins – reduced elastin and
adrenergic nerve density 🡪
increased caliber and distensibility
UTERINE
MUSCULATUR
E
3 strata/ layer

42. Uterus
LAYERS OF UTERUS
OUTER
Hood-like layer
Arches over fundus
MIDDLE
Dense network of muscle fibers
perforated in all directions by BLOOD
VESSELS
Forms MOST of the uterine wall
Forms FIGURE OF EIGHT
INNER
Sphincter-like fibers around the orifices
of fallopian tubes and internal cervical os

43. Cervix
• SOFTENING AND CYANOSIS 🡪 increased in vascularity
and edema, from changes in collagen and from hypertrophy
and hyperplasia of the cervical glands.
• CERVICAL RIPENING🡪 involves connective tissue
remodeling
○ Lowers collagen concentration
o Lowers proteoglycan concentration
○ Raises water content
• EVERSION🡪 marked proliferation of cervical glands
○ appears red and velvety
• CERVICAL MUCUS🡪 produced by endocervical mucous
glands; immunological barrier (rich in immunoglobulins and
cytokines)
• BEADING🡪 poor cryztallization; due to progesterone
• FERNING 🡪 amniotic fluid leakage

44. Ovaries
• Ovulation ceases during pregnancy, and maturation of new
follicles is suspended.
• Progesterone production : single corpus luteum 🡪 functions
maximally during the first 6 to 7 weeks of pregnancy.
• Diameter of the ovarian vascular pedicle🡪 increased from
0.9 cm to approximately 2.6 cm at term.
• Theca-Lutein Cysts🡪 benign ovarian lesions; an
exaggerated response of the ovaries to normal levels of
circulating hcG; self-limited and resolves following delivery.

45. Fallopian Tubes and Vagina
Fallopian Tubes
• Myosalpinx🡪 little hypertrophy during pregnancy.
• Fallopian tube torsion🡪 during uterine enlargement.
Vagina
• Violet color characteristic🡪 Chadwick sign
• pH is acidic, varying from 3.5 to 6.
• Vaginal walls🡪 undergo changes for distention
• epithelial thickening
• connective tissue loosening
• smooth muscle cell hypertrophy.

46. Breast Changes
• Breast enlargement 🡪 hypertrophy and hyperplasia of
the glands in preparation for lactation and also from an
inc. in the bulk of fatty tissue.
• Breast tenderness (mastodynia) and paresthesias
• End of 2nd month🡪 nipples become enlarged and erectile;
superficial veins become prominent; and areola widens, and
becomes more deeply pigmented.
• End of 1st trimester🡪 Colostrum, a thick yellowish fluid can
be expressed from the nipples
• Montgomery’s tubercles: enlargement of circumlacteal
sebaceous glands of the areola

47. 02
Cardiovascular System

48. Heart
• DISPLACED TO THE LEFT AND UPWARD, ROTATED ON ITS LONG AXIS
• APEX- move laterally and produced larger cardiac silhouette
• Slight LEFT AXIS DEVIATION
• Splitting of S1
• No changes in S2
• LOUD S3
• Systolic murmur – 90%
• Diastolic murmur – 20%
• Continuous murmur – 10%
• Increasing plasma volume 🡪 enlarging end- systolic and diastolic
• No change in septal thickness or ejection fraction
• Ventricular function – NORMAL

49. Heart
• Become apparent 🡪 first 8 weeks
• CO increases as early as 5th week
-reflects a reduced SVR and Increased HR
• Systolic BP, Diastolic BP, and Central
systolic BP all significantly lower 🡪 6-7
weeks from LMP
• Resting Pulse Rate 🡪 increases 10 beats/min
• Between weeks 10 and 20🡪 Plasma volume
expansion begins and preload rises 🡪Results in
significantly larger left atrial volumes and
ejection fractions
• REMODELLING- due increase levels of
estrogen and progesterone

50. Cardiac Output
🡪 Increased to about 30–50% during pregnancy, and the maximum increase is attained around 24 weeks’
gestation.
🡪 The increase is mediated by estrogen by increasing pre-load and stroke volume
🡪 Increased in Cardiac Output:
• Increased maternal oxygen consumption
• Hypervolemia
• Arteriovenous shunt effect of the placenta

51. Cardiac Output
Periods of increased cardiac output
• 28th week- highest peak of cardiac load.
• During labor
• Immediate post-partum
• first week of puerperium
Mechanism of Increased PLASMA VOLUME
• ESTROGEN and PROGESTERONE causes increase production of plasma renin which stimulates
aldosterone secretion which enhances sodium retention and increased body water.
• PROGESTERONE causes venous relaxation.

52. Blood Pressure
Blood
● ARTERIAL BLOOD PRESSURE
• systolic BP varies slightly
• there is reduced diastolic BP due to a decrease in peripheral
vascular resistance, thus pulse pressure increases
• at term BP normally returns to baseline levels
● VENOUS PRESSURE
• elevated in the lower extremities due to the increased blood
flow to the uterine vein and pressure of the gravid uterus on
the pelvic veins.
• PERIPHERAL VASCULAR RESISTANCE - REDUCED
in the lower extremities due to the increased blood flow to
the uterine vein and pressure of the gravid uterus on the
pelvic ns.

53. Natriuretic Peptides, Prostaglandins,
Endothelin, Nitric Oxide
RENAL MEDULLARY PROSTAGLANDIN E2 – - late pregnancy
PGI2 (PROSTACYCLIN) –
ATRIAL NATRIURETIC PEPTIDE (ANP) AND B NATRIURETIC PEPTIDE (BNP) – maintained
ENDOTHELIN 1 – potent vasoconstrictor
NITRIC OXIDE – vasodilator
🡪MOST IMPORTANT MEDIATOR OF PLACENTAL VASCULAR TONE

54. 03
Respiratory System

55. Pulmonary
Function
● ↓ Expiratory Reserve Volume (ERV)
● ↓ Functional Residual Capacity & Residual
Volume (FRC) (RV)
● ↓ or unchanged – Total Lung Capacity (TLC)
● ↑ Inspiratory Capacity (IC)
● ↑ Tidal volume (TV)
● ↑ Peak expiratory flow rate (PEFR), airway
conductance
● Forced vital capacity (FVC) – no significant
change
● Respiratory rate - unchanged
● Diagphragm 🡪 elevated during pregnancy.
● ↑ Subcostal angel 🡪Thoracic cage expands its
anteroposterior diameter causing flaring of the ribs.
● Breathing is more diaphragmatic than costal.

56. Acid-Base
▪ Hyperventilation
– attributable to progesterone
-- Progesterone increases ventilator drive by increasing the sensitivity of both central and
peripheral chemoreceptors to CO2.
● Hyperventilation occur🡪 increase in RR, increase in tidal volume (TV) by 30% to 40%, and increase in
minute ventilation by 40%.
● Increased TV🡪 lowers blood PCO2🡪 causing mild respiratory alkalosis 🡪 kidneys excrete bicarbonate
to compensate for the change in pH
● Oxygen consumption increases by 20% to 40% due to increased demand by the growing fetus,
placenta and increased metabolism of maternal organs

57. 04
Urinary System

58. Kidney
Kidney size – increases to approx. 1.5 cm
GFR and renal plasma flow - ↑
- 25% 2nd week after
conception
- 50% beginning of 2nd
trimester
Relaxin – important in mediating
increase GFR and renal blood flow

59. Kidney
Function Test
•Glucosuria
•
•Hematuria 🡪results from contamination during collection.
•Proteinuria
osignificant🡪excretion threshold of at least 300 mg/d is reached
oincreases with gestational age, which corresponds with the peak in GFR

60. Ureter and Bladder
URETER
● Dilatation🡪 due to compression.
● It is right sided in 86% 🡪 This unequal dilatation is due to cushioning effect of sigmoid colon on left
and dextro-rotation of uterus.
BLADDER
● Mucosa🡪increase in size and tortuosity of its blood vessels
● Near term, the entire base of the bladder is pushed forward and upward🡪convex to concave

61. 05
Gastrointestinal Tract

62. Upper & Lower GI
● Stomach and intestines🡪 displaced cephalad
● Gum Bleeding
● Pytalism- excessive salivation
● Pyrosis (heartburn)
● Prolonged transit time of GIT contents
-better ferrous, calcium and water absorption
-increase flatulence, and constipation
● Hemorrhoids
● Hepatobiliary
○ Increased risk of gall stones and cholestasis- due to reduced gallbladder contractility
○ Spider angiomata and palmar erythema
○ Decrease albumin and increase alkaline phosphatase and cholesterol

63. 06
Endocrine System

64. Human placental lactogen (HPL)
• Chorionic growth hormone or Chorionic somatomammotropin
• Detected as early as 2nd and 3rd wk of fertilization
• Rises steadily up to 34th to the 36th wk of pregnancy
Estrogen
• Biosynthesis 🡪 placenta, produced exclusively in the syncytiotrophoblast
• Production increases as pregnancy progresses terminating abruptly after the delivery of fetus and
placenta
• Adrenal glands 🡪 site of estrogen precursor substances that promotes placental estrogen
production
Progesterone
• synthesis 🡪 utilization of maternal plasma LDL to cholesterol in syncytiotrophoblast after the first

65. Pituitary Gland
• Anterior lobe🡪 hypertrophies to twice its size and increased in cellular acitivity of the pregnancy cells🡪
effect of estrogen stimulation
• Posterior lobe🡪 ↑ oxytocin (esp close to term)🡪 for stimulation of uterine contractility
Ovaries
• normal ovarian function is suppressed
• follicular maturation is suspended and theca interna cells undergo hyperplasia with luteinization
Thyroid gland
• undergoes hyperplasia🡪 hypervascularity and augmented function
• mild hyperthyroid state
• mild increase in thyroid hormones

66. Parathyroid Gland
• hypertrophy and hyperplasia🡪 enlargement and increased cellular activity
• Increasing PTH levels after 1st trimester result from increased plasma volume, increased GFR and
increase fetal transfer of calcium.

67. 07
Metabolic Changes

68. • An average gestational weight gain of 12.5 kg
• Additional pregnancy energy demand is 77,100kcal
• divided into approximately:
1st trimester- 85kcal/day
2nd trimester- 285kcal/day
3rd trimester- 475kcal/day

69. Carbohydrate Metabolism
• pregnancy is characterized by mild fasting hypoglycemia, postprandial hyperglycemia and
hyperinsulinemia
Lipid Metabolism
o concentration of triacylglycerols, fatty acids, cholesterol and phospholipids increase steadily after an
initial decrease in the first 8 wks
o increase insulin resistance and estrogen stimulation is responsible for the maternal hyperlipidemia
o increase lipid synthesis and food intake contribute to maternal fat accumulation during the first two
trimesters

70. Iron Metabolism
• 1000mgs of iron required for normal pregnancy
• 300 mg🡪 transferred to fetus and placenta
• 200 mg lost through normal excretion in GIT
• 500mg required for total circulating erythrocyte volume

71. 08
Hematologic Changes

72. Blood Volume
Increase by 40-45% above the non pregnant blood
Begins to increase in first trimester
Expands most rapidly in 2nd trimester and rises in
slower rate in 3rd trimester
Functions of hypervolemia
1. Meets the metabolic demands of enlarging
uterus and hypertrophied vascular system
2. Provides abundant nutrients and elements to
support rapidly growing fetus
3. Protects the mother from impacts of impaired
venous return

73. 09
Musculoskeletal System

74. • Round ligaments- found on the right and left
sides of uterus, attach to the pubic bone and
help support placement of uterus
• Ribcage- expands to make room for the
expanding uterus and maintain adequate lung
capacity
Progressive Lordosis
- Shifts the center of gravity back over the
lower extremities
-increase mobility🡪 Sacroiliac,
sacrococcygeal, and pubic joints
UPPER EXTREMITIES
• hand pain and numbness
🡪 swelling, fluid retention and increased blood
volume can restrict and compress tissues
• carpal tunnel syndrome –medial nerve
compression

75. 10
Skin

76. • Changes attribute to effects of estrogen, progesterone and
relaxin
PIGMENTATION
-due to increased melanocyte stimulating hormone:
1. Linea nigra
1. Choalasma or Melisma gravidarum-
-Butterfly pigmentation of the face (mask of pregnancy)

77. Diastasis Recti
Striae gravidarum
Palmar Erythema
Vascular Spiders – minute elevations on the skin of the face, neck, upper chest and arms
-also known as nevus, angioma or telangiectasia
-attributable to hyperestrogenism
-may be mistaken for manifestation of liver disease

78. 11
Central Nervous System

79. Memory
• Decreased attention, concentration, and memory
- Limited to 3rd trimester
- Transient and quickly resolve following delivery
• Poor verbal recall and processing speed, and worse spatial recognition memory
• Cerebral Blood Flow
- Mean BF in mid and posterior arteries DECLINE from 147 and 56 mL/min(non- pregnant) to 118 and
44 mL/min (late in pregnancy)
• Pregnancy does not affect cerebrovascular autoregulation

80. EYES
• Intraocular pressure drops
- Partly due to greater vitreous flow
• Corneal sensitivity decreased
- Greatest in late gestation
• Slight increase in corneal thickness
- Due to edema
- May have difficulty with previously comfortable contact lenses

81. Krukenberg spindles
• Brownish-red opacities on posterior surface of cornea
• Observed with a higher than expected frequency
during pregnancy
• Transient loss of accommodation

82. Sleep
• Difficulty sleeping beginning at 12 weeks AOG, extends through the 1st 2 months
• Difficulty falling asleep, frequent awakenings, fewer hours of night sleep, reduced sleep efficiency
• Sleep apnea
- Common in pregnancy, especially in obese patients
• Greatest disruption of sleep occurs postpartum
- May contribute to postpartum blues or frank depression

83. Thank
You.