Objectives: To determine short-term morbidities in late preterm infants (34^0/7 - 36^6/7 weeks of gestation) compared with term infants in Srinagarind Hospital and factors associated with late preterm births.

Materials and Methods: A prospective cohort study conducted by collecting and analyzing clinical data and short-term outcomes of late preterm and term infants born in Srinagarind Hospital during November 2009 to October 2010.

Results: During the study period, there were 2,199 live births. An overall preterm birth rate was 10.5%, and late preterm birth rate was 5.9%. Among 129 late preterm infants with mean gestational age of 35.4 ± 0.7 weeks and mean birth weight of 2,520.2 ± 470.2 grams, hyperbilirubinemia (53.5%) was the most common problem.  Neonatal intensive care unit admissions, hyperbilirubinemia, hypothermia, respiratory problems, infections, hypoglycemia and feeding problems in late preterm infants were significantly higher when compared with term infants. The most common diagnosis of respiratory problems included transient tachypnea of the newborn (72.7%) and respiratory distress syndrome (15.2%). Spontaneous premature labor was the most common risk factor associated with late preterm births (38.8%).

Conclusion: Late preterm infants had significantly higher short-term morbidities than term infants. Antenatal and perinatal care for prevention of late preterm births may reduce neonatal morbidities, mortality and costs of hospitalization.

Keywords: Late preterm infants, Term infants, Short-term morbidities, Late preterm birth, Risk factors