Chapter 28: Late Preterm Infants

Introduction

Although often considered healthy, especially in comparison to their extremely premature counterparts, a growing body of evidence shows these infants are at substantial risk of neonatal and long-term morbidities, as well as mortality.

The decision to proceed with delivery, whether medically indicated or secondary to preterm labor/premature rupture of membranes (PROM), requires balancing the consequences of continued pregnancy to both the mother and the baby.

I. Intensive care

Some, but not all of late preterm (LPT) infants will require intensive care, while others may be cared for safely in the term nursery. Available term nursery resources, including expertise with LPT infants and nursing availability, may dictate where the well-appearing LPT infant should be admitted.

1. Definition

   1. Infants born LPT are between 34 and 0/7 weeks' to 36 and 6/7 weeks' gestation.

   2. LPT infants are more likely to require assistance at delivery and their deliveries should be attended by at least one person with expertise in newborn care and resuscitation.

   3. Risk factors should be evaluated and assessment performed at delivery to allow proper admission of the infant to either the neonatal intensive care unit or the normal newborn nursery.

2. Incidence

   1. Premature infants account for more than 10% of deliveries; LPT infants constitute the largest portion of prematurely delivered infants accounting for over 71% of all preterm births.

   2. LPT infants frequently require intensive care unit (NICU) admission. Overall rates of NICU admission for LPT infants vary from 35% to 75% by center, with a smaller component of transfer from term nursery. Rates of NICU admission are inversely correlated with gestational age: 34 weeks: 43% to 100%, 35 weeks: 22.5% to 43%, 36 weeks: 12.3% to 40.5%.

   3. Many centers routinely admit all babies less than 35 weeks to a special care unit.

   4. Growing national and international awareness of the consequences of LPT birth has finally led to a decrease in birth rates: following a steady increase in the number of infants born LPT since 1981, this number has now decreased each year since 2006. However, more than 339,000 LPT infants born in the United States in 2010 still create a substantial economic and health care burden.

3. Pathophysiology

   1. LPT infants are at risk for illness at birth due to both their immaturity and a high incidence of complicated pregnancies in this group.

   2. LPT infants are often the product of a medically complicated pregnancy and delivered by cesarean section, which further increases the risk to the neonate.

   3. Immaturity causes delayed clearance of lung fluid, risk of respiratory distress syndrome, and increased risk of apnea.

   4. LPT infants are also at increased risk for hypothermia, hypoglycemia, and feeding difficulties due to their small size and immature feeding skills.

   5. There is also a higher risk on neonatal sepsis in pregnancies complicated by PROM and chorioamnionitis.

4. Risk factors

   1. Birth at each week earlier in gestation is a strong risk factor for NICU admission.

   2. Maternal illness, including diabetes ...