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32-36 Week Infants

32-36 Week Infants. Stacie Bennett, M.D. East Bay Newborn Specialists September 12, 2007. Definitions. Full Term >37 weeks of gestation Preterm <34 weeks of gestation Late preterm 34 0/7-36 6/7 weeks of gestation Normal BW >2500grams LBW <2500g VLBW <1500g ELBW <1000g. Statistics.

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32-36 Week Infants

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  1. 32-36 Week Infants Stacie Bennett, M.D. East Bay Newborn Specialists September 12, 2007

  2. Definitions • Full Term >37 weeks of gestation • Preterm <34 weeks of gestation • Late preterm 34 0/7-36 6/7 weeks of gestation • Normal BW >2500grams • LBW <2500g • VLBW <1500g • ELBW <1000g

  3. Statistics • Rate of preterm birth in US increased from 9.1% in 1981 to 12.3% in 2003. • 2/3 of this increase was due to late preterm births. • ~74% of preterm births are late preterm infants from 34-36 weeks of gestation. • This leads to huge impact on health care.

  4. Statistics • ~50% of infants born at 34 weeks require intensive care. • ~15% at 35weeks. • ~8% at 36 weeks.

  5. Late Preterm Infant • In 2005 the NICHD had a workshop to address the issues and impact of these late preterm infants. • Prior to this meeting these infants were called “near term”. • These infants have significantly higher rates of morbidities and mortalities compared to term infants and should be considered preterm.

  6. Neonatal Issues of Late Preterm Infants • Temperature Instability • Hypoglycemia • Respiratory distress • Apnea • Increased mortality and risk of SIDS • Increased risk of sepsis/antibiotic exposure • GI problems and feeding difficulties • Hyperbilirubinemia • Increased readmissions • Long term neurodevelopmental problems

  7. Temperature Instability • Hypothermia: rectal temperature <36.5 degrees C. • Late preterms are at increased risk for hypothermia through the first 24 hours of life. • Probably secondary to immature epidermal barrier, increased surface area to weight ratio, more delivery room intervention preventing bundling, but also may be a sign of sepsis. • 10% of infants at 35-36 weeks and ~0% at term require some type of management for hypothermia.

  8. Temperature Instability • Clinical signs of hypothermia include: tachypnea, poor color due to vasoconstriction, low heart rate, and metabolic acidosis. • Management: • Delivery room: routine NALS, warmers, skin to skin. • ICN: may include skin to skin contact for larger stable infants, or extra bundling and hats, but often require a radiant warmer or isolette to maintain normal temperature (36.5-37.4 degrees C). • Important to follow temperatures frequently for the first 24 hours.

  9. Hypoglycemia • Late preterms are at increased risk for hypoglycemia requiring treatment. • ~18% at 35-36 weeks and 4% at term develop hypoglycemia. • 2/3 of these infants require treatment with IV dextrose. • The etiology is felt to be secondary to delay in hepatic glucose-6-phosphatase activity, low body fuel stores, inadequate oral intake, or other risk factors such as hypothermia and sepsis that increases metabolic demand.

  10. Hypoglycemia • The main concern: glucose is the primary substrate for cerebral metabolism. • In preterm infants moderate hypoglycemia with glucose <47mg/dL has been shown to have neurodevelopmental consequences. • Hypoglycemia can occur during the first 24 hours and needs to be monitored. • Treatment may include: • A nipple trial of formula or D10W if infant is able to. • If unable to nipple, will require IV fluid with a D10W bolus of 2-3ml/kg followed by a dextrose infusion.

  11. Respiratory Issues • Increased risk for RDS, pulmonary hypertension, TTN, and Pneumonia(?). • RDS can occur in ~12% of 33-34 wk, 2% of 35-36 wk, and 0.11% in term infants. • TTN can occur in 11.6% of 33-34 wk, 5% of 35-36 wk, and <1% in term infants. • Overall, ~31% of 35-36 weeks will have some respiratory distress requiring some management vs ~ 4% for term.

  12. Respiratory Issues • Etiology for distress is possibly due to lack of clearance of fluid with immature Na transport channels or surfactant deficiency. • Must monitor for signs of distress: tachypnea, nasal flaring, retractions, grunting, oxygen need. • Management may include: • Monitoring • Oxygen via a hood or nasal canula • Use of nasal continuous positive airway pressure • Intubation and surfactant therapy • These infants are also at increased risk for apnea (4-5% at 34-36 weeks and ~0% at term) and must be monitored.

  13. Infection • Late preterm infants are more likely to be evaluated for sepsis and treated for presumed or actual infection. • Therefore they have more antibiotic exposure. • If an infant has respiratory distress, hypoglycemia, or hypothermia, it can be a sign of infection and may require a septic w/u including antibiotics. • Perinatal history is also important, such as maternal chorio or prolonged rupture of membranes, as GBS status is often unknown at these gestations.

  14. GI/Feeding Issues • Late preterm infants have less mature peristaltic function and sphincter control. • They are at increased risk for necrotizing enterocolitis (NEC). • They can also have uncoordinated suck and swallow, poor weight gain, and dehydration. • Management: • IVF and parenteral nutrition until enteral feeding improves. • Gavage feeds until oral feeding improves. • Supplementation of breast milk with formula or higher calorie supplementation if inadequate weight gain.

  15. Jaundice • Late preterms have an increased incidence of hyperbilirubinemia. • This often leads to delayed discharge and an increased rate of readmission. • They appear to be at increased risk for bilirubin induced brain injury. A large proportion of infants with kernicterus are late preterm infants. • Management: These infants need to be monitored closely for jaundice. Consider checking a bilirubin prior to discharge and plotting it on the graphs in the AAP guidelines if >35 weeks. These infants need close follow up after discharge.

  16. Readmission • Increased rate of readmission: • 5.3-9.6% for infants from 33-37 weeks. • 3.6-4.4% for term infants. • Readmission may be secondary to jaundice, poor weight gain, dehydration, or other etiologies. • They need close follow up as outpatients.

  17. Mortality • Increased mortality from all causes compared to infants born at term. • 7.7/1000 in late preterm infants vs 2.5/1000 in term infants. • 2 X greater risk for SIDS. • 1.4/1000 in late preterm infants vs 0.7/1000 in term infants; mechanism is unknown.

  18. Brain • Late preterms have more immature brains. • Weight is 60% of that at term. • Decreased sulci/gyri/synapses. • Some studies suggest increased risk of periventricular leukomalacia seen at autopsy. • These infants are at increased risk for cerebral palsy as compared to term infants.

  19. Long Term Outcome • Limited data. Studies are primarily based on surveys. • In follow-up studies, infants born at 32-35 weeks can have ~1/3 with some learning/behavioral difficulty. • ~20% of 34-37 week infants can have some learning difficulties compared to <10% of those born at term. • Other data suggest increased rates of ADHD and other behavioral problems.

  20. What to do? • Need more information. • ? Best obstetric management, ? Later steroids, ? Check for fetal lung maturity. • ? Elective c/sections. • Best neonatal management- well baby vs ICN. • Better studies evaluating long term follow up and how to improve outcomes.

  21. 32-33 week infant • Same complications of the late preterm infant, though increased frequency. • Require ICN admission. • Infants between 30-34 weeks ~ 46% require assisted ventilation (CPAP or intubation) • Most if not all require IV fluids and TPN. • Prior to 34 weeks most infants can’t nipple all feeds and require gavage feedings. • They are at risk for problems seen in more preterm infants. • Even higher risk for developmental problems and readmissions.

  22. Overall • Infants <34 weeks and <2100 grams: admit to ICN, neonatology consult and perhaps transfer. • 34-36 weeks: close observation for all of the above issues before transferring to well baby. • Don’t discharge early. • Close follow up after discharge and into childhood.

  23. Bibliography • Raju, Higgins, Stark, Leveno. Optimizing care and outcome for late-Preterm Infants: A summary of the workshop sponsored by the National Institute of Child Health and Human Development. Pediatrics 2006; 118:1207-1214. • Wang, Dorer, Fleming, Catlin. Clinical Outcomes of Near-Term Infants. Pediatrics 2004; 114: 372-377. • Kirkegaard, Obel, Hedegaard, Henriksen. Gestational Age and birth weight in relation to school performance of 10 year old children. Pediatrics 2006; 118: 1600-1607. • Stein, Siegel, Bauman. Are children of moderately low birth weight at increased risk for poor health? Pediatrics 2006; 118: 217-224 • Engle. A recommendation for the definition of “late Preterm” and the birth weight-Gestational age classification system. Seminars in Perinatology 2006; 30: 2-7 • Laptook, Jackson. Cold Stress and Hypoglycemia in the late preterm infant. Seminars in Perinatology 2006; 30: 24-27 • Escobar, et al. Unstudied infants: outcomes of moderately premature infants in the neonatal intensive care unit. Archives of diseases of childhood 2006; 91; F238-244. • Shapiro-Mendoza et al. Risk factors for neonatal morbidity and mortality among “healthy’ late preterm newborns. Seminars in Perinatology. 2006; 30: 54-60. • Huddy, Johnson, Hope. Educational and behavioral problems in babies of 32-35 weeks gestation. Archives of diseases of childhood fetal and neonatal edition. 2001; 85: F23-28. • Jain, Eaton. Physiology of Fetal lung fluid clearance and the effect of labor. Seminars in perinatology 2006; 30: 34-43.

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