Late Preterm Infants: Immediate problems after birth

Last modified: Sunday, October 6, 2019
Any baby born before 37 completed weeks of gestation are preterm babies.
Looking at the pathophysiology of babies who are extremly tiny and who are mature, there is a transitional range of babies in between called Late Preterm babies. Late preterm babies are those who are born 34 to 36 weeks and 6 days.
[Late preterm” was defined by participants of the 2005 Workshop on “Optimizing Care and Outcome of the Near-Term Pregnancy and the Near-Term Newborn Infant”  National Institutes of Heath ].

late preterm baby

Term neonates are those who are born between 37 completed weeks of gestation to 41 weeks and 6 days. Those babies who are born between 37 weeks and 38 weeks 6days are Early Term babies. Full Term babies are those who are born after 39 weeks.
Post term newborns are those born after 42 completed weeks of gestation.

preterm definitions

Late Preterm Infants

Late preterm infants are often notrious in any NICUs. They are metabolically and functionally immature and often present with mutitudes of problem, while some of them behave like full mature term infants and transit uneventfully.

Some of the commonly encountered problems in Late preterm neonates are

Respiratory distress

As late preterm babies tend to have delayed cardiopulmonary adaptation to ex-utero environment, they present with Transient Tachypnea of Newborn and Hyaline membrane disease. They are more prone to developing pneumothorax because of secondary lung pathologies like RDS.


One of the dreaded complication of any pathology in neonates in Persistent pulmonary Hypertension of Newborn which is rarer in extreme preterms and more common in Late preterm and term babies.

Apnea of Prematurity: 

Although rare, 4-7% of LPT babies can develop apnea due to functional immaturity of the Central nervous system.


As they have low brown adipose tissue response, late preterms are more prone to Hypothermia.


Jaundice during neonatal period is a frequent problem in LPT infants due to functional immaturity of Liver enzymes. The duration of jaundice is often more prolonged, and peak concentrations of indirect bilirubin frequently are higher than found in term infants. Delayed maturation and lower concentrations of uridine diphosphoglucuronate glucuronosyltransferase, Increased enterohepatic circulation, increased RBC load lead to development of exaggerated neonatal jaundice in this age group.

neonatal jaundice phototherapy

Feeding Problems

Poor Suck-swallow coordination, feeding intolerance and seldom Nectrotizing enterocolitis are seen in these infants.

Metabolic and other Problems

Hypoglycemia, Hypocalcemia and Polycythemia are specifically seen problems in late preterm infants. Polycythemia and hypoglycemia are more common in IUGR infants.
Some of the References Quoted them as: 1. 'Late preterm infants: near term but still in a critical developmental time period.' Kugelman A Pediatrics 2013 
2. 'Late preterm Infants: A population at risk' William A, Pediatrics 2007 Neoreviews: Infant born Late preterm




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