On the Brink of Birth

A full term fetus, is shown in its mother’s womb in this Leonardo da vinci drawing. One of the first accurate renderings of a part of the human anatomy. The smaller sketches depict details of the uterus. Of all the triumphs of the body, its crowning glory is the power to reproduce its kind and pass some of its hereditary characteristics on to later generations.

Embryo to Fetus

fifteen days twenty-one days thirty days thirty-four days six wks eight wks

Life: One Seed + One Egg Life begins when an egg, previously released from one of the two ovaries, merges with just one of the hundreds of millions of sperm cells supplied through the vagina by the male reproductive system. The fertilized egg then descends to the wall of the uterus, where it implants itself to begin gestation.

Fetus

The average weight of the Indian baby at 40 weeks of

pregnancy is 2,750Gms at birth.

New Born

A healthy new born cries vigorously as soon as he is born, kicking his limbs actively, giving the greatest joy to the tired mother.

INTRODUCTION

Pregnancy causes physiologic changes in all maternal organ systems; most return to normal after delivery.

In general, the changes are more dramatic in multifetal than in single pregnancies.

Major adaptations in maternal anatomy, physiology, and metabolism.

BODY WATER METABOLISM

Condition of chronic water overload

Active Na and water retention

1. Changes in osmoregulation

2. Renin-angiotensin system

Body water increase 6.5L 8.5L

1. 1500 cc increase in blood vol

2. RBC increase ~400cc

OSMOREGULATION

Na retention increases 900 mEq but serum Na decreases 3-4 mmol/l

Plasma osmolarity decreases 10 mOsm/kg

Enhanced tubular reabsorption of Na secondary to aldosterone,estrogen and deoxycorticosterone.

CARDIOVASCULAR CHANGESHeart Displaced to the left and upward Apex is moved laterally Apparent cardiomegaly on chest x-ray Increase in left ventricular end-diastolic dimension Cardiac output (CO) increases

RESPIRATORY CHANGESUpper Respiratory Tract Hyperemia and edema induced by estrogen Nasal stuffiness and epistaxis

Mechanical changes

earlier than mechanical pressure of rising uterus Chest circumference expands 5-7 cm Subcostal angle increases from 68 to 103 degrees Transverse diameter increases 2cm Level of diaphragm rises 4cm but excursion is not

impeded Respiratory muscle function is not affected by

pregnancy

LUNG VOLUME AND PULMONARY FUNCTION

Elevation of the diaphragm decreases the volume of the lungs in the resting state, reducing Total Lung Capacity (TLC) by 5%

Functional Residual Capacity (FRC) by 20% FRC mainly decreased by Residual Volume (RV)

Vital capacity does not change Spirometry is not changed in pregnancy

Forced Expiratory Volume in 1 sec (FEV1) is unchanged

Peak flow is unchanged

HEMATOLOGIC CHANGES

40-50% increase in blood volume beginning at 6 weeks and plateaus at 30 weeks

Both plasma volume and cell mass increase

Physiologic anemia of pregnancy at 30 weeks

Increase in erythropoietin and reticulocyte count

IRON METABOLISM Iron (Fe) bound transferrin transported to

liver, spleen, muscle and bone marrow incorporated into hemoglobin and myoglobin

1000mg iron requirement, about 3.5 mg/dL of Fe

Requirements increase in third trimester

Fetus receives Fe through active transport

IRON SUPPLEMENTATION

Iron supplementation usually not needed before 20 weeks

30mg of elemental FE 325 mg ferrous gluconate

Fe supplements

Ferrous sulfate ( 65mg elemental Fe)

Ferrous gluconate (35mg of elemental Fe)

PLATELETS

Progressive decline in count from 1st-3rd tri

Increased platelet destruction

Gestational thrombocytopenia of pregnancy

OTHER HEMATOLOGIC CHANGES

Leukocytosis secondary to neutophils Estrogen induced Cortisol induced

Altered immune status Modulation away from cellular immunity

towards humoral immunity Paradoxical decline of immunoglobins A,G,M Only IgG crosses the placenta

URINARY SYSTEMAnatomic Changes Renal hypertrophy Dilation of renal pelvis/calyces

15mm on the right in 3rd trimester

5mm on the left

Predisposition to pyelonephritis in the presence of asymptomatic bacteriuria

Dilation of ureters to 2 cm Mechanical compression Progesterone-induced smooth muscle

relaxation

BLADDER CHANGES

Bladder trigone elevation occurs with increased vascular tortuousity throughout the bladder leading to microhematuira

Decrease bladder capacity

Increased frequency of micturition.

DIGESTIVE TRACT CHANGES

Addition of 300 kcal/day Gingivitis of pregnancy Stomach

Gastroesophageal refluxGastric compression due to enlarging

uterus

Decrease sphincter tone

Small bowel

Motility is reduced due to progesterone allowing for more efficient absorption

Large bowel

Decreased transit times allows for both water and sodium absorption

Liver Size and histology are unchanged Clinical and laboratory changes mimic disease

states Palmar erythema

SKELETAL AND POSTURAL CHANGES

Lordosis of pregnancy~ progressive increase in anterior convexity of the lumbar spine

Preserves center of gravity

Ligaments of the symphysis and sacroiliac joints loosen during pregnancy due to relaxin

ENDOCRINE CHANGES

Thyroid Physiology Euthyroid state Increase in thyroxine-binding globulin Slight thyromegaly T4 and T3 remain normal Fetal thyroid active by 12 weeks gestation

Adrenal function Increases in corticosteroid-binding globulin Increases in free cortisol Zona fasciculata is increased Marked increase in CRH from placental

sources Delayed plasma clearance of cortisol due to

renal changes Resetting of hypothalamic-pituitary sensitivity

to cortisol feedback on ACTH production

Pituitary gland Enlarges due to proliferation of prolactin-

secreting cells Enlargement makes it more susceptible to

alterations in blood flow, ie PPH Prolactin levels are increased (ten times higher

at term) to prepare breasts for lactation

Pancreas and Fuel Metabolism Physiologic glucose intolerance to ensure

continuous transport of nutrients from mother to fetus

Fasting hypoglycemia Postprandial hyperglycemia Hyperinsulinemia

Diabetogenic effects of pregnancy

Cortisol

Prolactin

Estrogen and progesterone

Fetal glucose levels are 20 mg/dl less than maternal values

INTEGUMENTAL CHANGES

Hyperpigmentation 90% of pregnancies

Localized to areas of increased melanocytes

Chloasma of pregnancy