Ma. Luisa de Villa-Manlapaz, MD, MHPEd February 8, 2011 ASMPH

Learning Objectives To review the fetal circulation To learn the changes in the pulmonary and cardiovascular system that occur during birth To learn the hepatic adaptations in glucose metabolism, bilirubin metabolism, and vitamin K production To learn how a newborn achieves thermoregulation

Fetal Circulation Placenta is responsible for exchange of gases, nutrients and metabolic waste products Fetus receives blood from the placenta and returns it to the placenta

Fetal Circulation Blood flows from the placenta into the umbilical vein The blood which contains a PO 2 of approx 35 mmHg passes through the liver and ductus venosus

Fetal Circulation Blood from ductus venosus drains into the inferior vena cava  foramen ovale  left atrium

Fetal Circulation Superior vena cava drains de-oxygenated blood from the brain into the right atrium.  right ventricle. 90% of blood from RA shunted through the ductus arteriosus 10% ejected to pulmonary artery  lungs

Fetal Lungs and Circulation Alveoli filled with lung fluid Pulmonary arterioles constricted Pulmonary blood flow diminished 1-7 Click on the image to play video

Neonatal Circulation After birth, umbilical cord is cut Systemic vascular resistance increases (BP in aorta increases) Pulmonary vascular resistance decreases ((BP in lungs decreases)

Lungs and Circulation After Delivery Lungs expand with air Fetal lung fluid leaves alveoli 1-9 Click on the image to play video

Lungs and Circulation Pulmonary arterioles dilate Pulmonary blood flow increases 1-10

Lungs and Circulation Blood oxygen levels rise Ductus arteriosus constricts Blood flows through lungs to pick up oxygen 1-11

Normal Transition Fluid in alveoli absorbed and replaced by air Umbilical arteries and vein constrict thus increasing blood pressure Blood vessels in lungs relax, increasing pulmonary blood flow 1-12 The following major changes take place within seconds after birth:

Baby cries and take first breath which help open alveoli Surfactant keeps the alveoli from collapsing after they expand

Metabolic Adaptation In utero, fetus relies primarily on placental transfer of glucose and nutrients from mother to meet energy demands

Metabolic Adaptation Fetus stores glucose in the form of glycogen in last trimester – especially in last month of trimester

After Birth Enzymes activate breakdown of glycogen back into glucose molecules Glucose released into bloodstream to maintain blood sugar Normal glucose utilization rate in fasting healthy term infant is 4-6 mg/kg/min

Factors which influence glucose levels Glycogen stores Insulin levels Glucose utilization Premature baby Infant of diabetic mother Sick infant

Thermoregulation In utero, the fetus is in a warm and dark environment Temperature is controlled

At birth, newborn has to produce as much heat as much as is lost THERMOREGULATION

Normal Response to Cold Stress Vasoconstriction in arms and legs Increased movement and flexion of extremities Brown fat metabolism

Brown Fat Metabolism

Heat loss Occurs on a gradient from warmer to cooler Baby’s warm body to cooler air or surface Heat loss accentuated by: Wet skin Cool air temperature Drafts

Kangaroo mother care Mother provides warmth to the baby by skin to skin contact. Provides easy access to the breasts, promoting breastfeeding

Hepatic adaptation Minor role of fetal liver – portal circulation shunted through the ductus venosus Majority of bilirubin pigment transferred unaltered across the placenta to the maternal circulation Fetus has a high percentage of circulating red blood cells to utilize all available oxygen in a low oxygen environment

PHYSIOLOGIC JAUDICE Increased bilirubin load on liver cell Increased erythrocyte volume Decreased erythrocyte survival Increased enterohepatic circulation of bilirubin Immature liver function

Hepatic Adaptation Liver manufactures clotting factors needed for blood coagulation Several factors need Vitamin K for their production Bacteria that produce Vitamin K are normally found in the gastrointestinal tract

However, the gastrointestinal tract of the newborn is sterile Therefore newborn cannot manufacture vitamin K which is needed to produce some clotting factors Newborns are given Vitamin K either intramuscularly or orally at birth to prevent bleeding disorders

Learning Objectives To review the fetal circulation To learn the changes in the pulmonary and cardiovascular system that occur during birth To learn the hepatic adaptations in glucose metabolism, bilirubin metabolism, and vitamin K production To learn how a newborn achieves thermoregulation

Brazelton’s States of Reactivity 1. Deep sleep: quiet, non-restless sleep state 2. Light sleep: eyes closed but more activity is noted; newborn moves actively; may show sucking behaviour 3. Drowsy: eyes open and close and eyelids look heavy; body activity is present with episodes of fussiness

4. Quiet alert: quiet state with little body movement, but the newborn’s eyes are open and she is attentive to people and things that are near her 5. Active alert: eyes are open and active body movements are present; newborn responds to stimuli actively 6. Crying: eyes may be tightly closed, thrashing movements are made together with active crying