Maternal Physiology Flashcards
Uterus from 70g becomes
1100 g
Uterus from 10ml becomes
5 L
Changes in uterine muscle
Hypertrophy and hyperplasia (under influence of hormones estrogen and progesterone)
Stretching beyond 20 weeks (1.5 cm or less)
Arrangement of uteirne muscle fiber
Outer hood-like layer
Middle layer (figure of 8), forms uterine wall
Internal layer - sphincter-like fibers
Important postpartum minimizing hemorrhage
Uterus shape
spherical by 12 weeks
Uterus position in cavity
Displaces intestine laterally and superiorly
Ascends from pelvis then rotate to the right (dextrorotation) which is likely caused by rectosigmoid on left side
At term uteroplacental blood flow
450-650 ml
Ave 550ml/min
There is increased venous caliber and distensibility of uterine blood vessels due to
Remodelling from reduced elastin content and adreneglrgic nerve density
With advancing gestational age, uteroplacental blood flow is regulated by vasodilation by
estrogen
Softening and cyanosis of cervix due to increased vascularity and edema
hypertrophy and hyperplasia of cervical glands
Goodell’s sign
Red and velvety cervix due to marked proliferation of columnar endocervical glands
Bleeds with minor trauma
Eversion
Labor ensues once bloody show occurs in
1-2 days
Arborization of crystals
Ferning - amniotic fluid leak
Endocervical gland hyperplasia and hypersecretory appearance induced by estrogen
Arias-stella reaction
Discoloration violet of vagina due to hyperemia secondary to increased vascularity
Chadwick’s sign
Inc in vaginal discharge: thick and white
vaginal pH
3.5-6.0
inc in lactic acid production by Lactobacillus acidophilus (Nitrazine test)
Pregnancy mask
Extreme form of pigmentation around the cheek, forehead and around the eyes
May be patchy or diffuse and disappears spontaneously after delivery
OCPs cause similar pigmentation
Chloasma gravidarum
Skin changes
Striae gravidarum Linea nigra Spider angioma Palmar erythema Diastasis recti
Increase in basal metabolic rate
10-20%
20-30% in twin gestation
Energy demand/trimester
1st - 85
2nd - 285
3rd - 475
Total weight gain
27.5 (12.5 kg)
At term, the fetus, placent and AF contains how much fluid
3.5 L 3 L (maternal blood volume)
Min amount of extra water: 6.5 L
Inc plasma osmolality by 10
Protein is regulated by
Placenta - protein synthesis, oxidation and transamination of NEAA
Higher nitrogen balance
Carbohydrates in pregnancy
Mild fasting hypoglycemia
Postprandial hyperglycemia
Hyperinsulinemia
Hyperplasia and hypertrophy of beta cells
Switch in fuel from glucose to lipids
Accelerated starvation
GH-like hormone that increases lipolysis
Inc in lipolysis -> inc FA -> inc tissue resistance to insulin
Maternal hyperlipidemia - inc insulin resistance and estrogen stimulation
Inc lipolytic activity and dec lipoprotein lipase activity in adipose tissue
Placental lactogen
Maternal blood volume inc to
45% near term
Expands rapid during 2nd tri
Inc in plasma and erythrocytes causing dilutionak anemia of pregnancy
Functions of pregnancy induced hypervolemia
Meet metabolic demands
Abundance of nutrients and elements to support placenta and fetus
Protect mother and fetus against deleterious effects of impaired venous return in supine and erect
Safeguard mother against adverse effects of blood loss
Amount of iron needed in pregnancy
1000mg iron
300mg ferrous sulfate, twice if anemic
Blood cell changes
Leukocytosis
Thrombocytopenia - below 25th percentile due to inc consumption and hemodilution
Hypercoagulable, Thromboembolism
Inc Fibrinogen (Factor 1) by 50%
Inc F 8
Inc F 7,9,10 and 12
Shortened PT, PTT
Dec FIBRINOLYTIC activity
Changes in CV system
Inc SV
Inc HR by 10 bpm
Inc CO
Inc O2 consumption
Dec SVR
Dec SBP
Dec DBP
Dec MBP
Changes in ECG
Inc HR
15 deg LAD
Changes in CXR
Heart larger
Displaced, left, upward and rotated as a result apex is moved somewhat laterally from its usual position causing a larger silhouette
Cardiac sound
Exaggerated splitting of 1st heart sound with inc loudness
Loud 3rd sound
Soft and transiet murmurs
90% has systolic murmur during inspiration disappears shortly after delivery
Cardiac output
Inc due to
dec in MAP
dec in VR
inc in BV and BMR
CO is position dependent
supine - diminished
left lateral cubitus - inc by 20%
Dec in 10% CO in supine patients
Significant arterial hypotension
Uterine arterial pressure and blood flow is lower than brachial artery directly affecting fetal heart patterns
Compression of inferior vena cava
Dec venous return
Dec CO output
Lower BP
Supine hypotensive syndrome
No fall in blood pressure because of reflex vasoconstriction
Concealed caval compression
In left lateral cubitus, fetal oxygenation is higher
Highest peak of CO
Inc plasma volume and heightened oxygen demand of fetus
28-32nd week
Periods of inc CO
28-32nd week
Labor
Immediately after delivery
First week puerperum (6 weeks after childbirth)
Peripheral vascular resistance falls during pregnancy due to
Progesterone’s relaxing effect on smooth muscle
Dec in PVR leads to fall in SBP during first 24 weeks
Venous blood pressure
Unchanges in UE
Inc in LE especially supine sitting or standing returns to normal in lateral decubitus
Occlusion of pelvic veins and IVC hence edema
PCWP
CVP
No change
Changes in respiratory tract
Diaphragm rises to 4cm
Subcowtsl angle widens
Transverse diameter of thoracic cage by 2cm
Thoracic cirumference by 6cm
Pulmonary function
DEC FRC by 20-30% (Dec ERV by 15-20; Dec RV by 20)
Inc IC by 5-10 Inc/unchanged TLC by 5 RR unchanged Inc TV by 30-50 Inc RMV (inc respiratory drive from progesterone, low expiratory reserve volume and compensated respi alkalosis)
Maternal AV oxygen difference
Decreased
amount of O2 delivered to lungs by inc TV exceeds O2 requirement
Total oxygen carrying capacity increased due to inc total hemoglobin mass
Inc CO
SOB is a complaint due to
Inc TV that lowers PCO2
Over breathing by progesterone acting centrally to lower threshold and inc senstivity of chemoreflex response to CO2
Shift to the left (Bohr)
Offset by inc 2,3 DPG to the right (Haldane)
Urinary changes
Uterus rises above pelvis resting upon ureters laterally displacing and compressing them at pelvic brim
Dilatation of collecting system because of progesterone and compression of ureter
Physiologic hydroureter: R ureter is compressed more than left because
Dextrorotation of uterus
Sigmoid on left cushioning the ureter
Greater kinking of ureter due to internal iliac within the pelvic brim
Right ovarian complex passes obliquely over the ureter
Urinary physiologic changes
Inc renal plasma flow RPF
Inc glomerular filtration rate by 50%
expect glucosuria
DEC serum creatinine and BUN
Inc frequency of micturition
GI Tract
Pregnancy gingivitis - hyperemia and softened bleeding gums
Appendix displaced laterally and upwards
Dec tone and motility of GIT
Pyrosis (heart burn), dec LES
Hemorrhoids
Focal, highly vascular swelling of gums
Pyogenic granuloma that occasionally develops but regresses spontaenously after delivery
Epulis gravidarum
Impaired GB contraction
High residual volume
inhibition of CKK by
Progesterone
Inc bile cholesterol saturation -> inc stones for multiparous
Pituitary gland inc in size by
135%
GH - same as nonpregnant
-at 17 weeks, placenta (synciotrophoblast)primary source differs by 13 AA
Major determinant of maternal insulin resistance in mid pregnancy
GH by synciotrophoblast
Inc by 10 fold (150)
Estrogen stimulation
TRH
Serotonin
Prolactin
Ensures lactation of delivery by acting to initiate DNA synthesis and mitosis of glandular epithelial cells and presecretory alveolar cells of the breast
Inc estrogen and prolactin receptors
Promotes mammary gland galactopoiesis and production of casein, lipids and lactose
Prolactin
Prolactin is produced in amniotic fluid (10,000) at 20-26 weeks by
Prevents fetal dehydration by impairing water transfer from fetus to maternal compartment
Uterine decidua
Thyroid gland changes
Euthyroid
Enlarges by hyperplasia and vascularity
Inc production of thyroid hormones 40-100%
Does not cause thyromegaly
Early trimester thyroid changes
TBG inc and peaks to 20 weeks
FT4 rise slightly and peak with HCG returns to normal
Total serum T4 inc and peaks up to 18 weeks
TRH does not inc but crosses placenta to stimulate pituitary to secrete TSH
TSH and HCG similar alpha components
Elevated HCG affects alpha of TSH manifested as thyroid storm in H moles
Musculoskeletal changes
Inc mobility of SI, SC, pubic joints
Relaxation of pubic symphysis >1 cm
Regresses and resolves 3-5 months postpartum
CNS Changes
Memory decline 3rd trimester (attention, concentration, memory)
Sleep - difficulty 12 weeks to first 2 months
