In this issue of Indian Pediatrics, Gupta and colleagues [3] report the results of a prospective longitudinal cohort follow-up study of 200 late preterm infants and 199 term controls. The participating infants were enrolled from a single center in Northern India, predominantly from the lower socioeconomic class, and details of medical morbidities, mortality and growth measures were collected at 12 months chronological age. The follow-up rate was fair at about 80%. Consistent with previous reports, the late preterm cohort experienced a greater incidence of feeding difficulties, jaundice, fever and diarrheal episodes, and re-hospitalization through a year of age. Exclusive breastfeeding was lower and difficulties in latching were reported by care-givers, which could have been the antecedent to the infectious complications during infancy. The striking finding of the study was the 4.1-fold risk of being underweight at 12 months among healthy late preterm infants, after adjustment for maternal weight, gender, socioeconomic status and exclusive breastfeeding. One previous population-based study from Brazil showed an increased risk of being underweight at both 12 and 24 months of age among late preterm infants [4]. The current study [3] confirms growth failure during infancy, but shows a lower rate of weight gain during infancy in late preterm infants. The rate of increase of head circumference was higher than among term controls and length gain was comparable in the two groups; these results may suggest the beginning of catch-up growth. In a recent study [5] in 108 late-preterm individuals, for every standard deviation faster weight and head growth from birth to 5 months and head growth from 5-20 months corrected age, there was a 0.19-0.41 standard deviation increase in IQ at 24-26 years of age. In contrast, rapid catch-up growth is thought to be associated with obesity, adverse lipid profile and chronic diseases in adulthood. In any case, whether the growth failure at 12 months is transient or persists into adulthood, the implications are serious. In a systematic review of studies from low- and middle-income countries [6], undernutrition in childhood was associated with high glucose concentrations and elevated blood pressure in adulthood, after adjustment for adult body mass index and height. The finding of growth failure until 12 months of age in a cohort of well appropriate-for-gestational age late preterm neonates, who did not manifest any neonatal signs of immaturity, is sobering.

Another finding of the study by Gupta, et al. [3] was that mortality until 12 months of age was statistically comparable between late preterm infants and their term-born counterparts, although the raw number of late preterm infants who died was more than double the term infants. In a previous study [7] using linked birth and death data in the United States over several years, infant mortality rates in the year 2002 were 3 times higher in late-preterm infants than term infants (7.9 versus 2.4 deaths per 1000 live births); early, late, and post-neonatal rates were 6-, 3-, and 2- times higher, respectively. During infancy, the leading causes of death in late preterm infants were congenital malformations (leading cause), newborn bacterial sepsis, and complications of placenta, cord, and membranes. The current study failed to show a difference in mortality probably due to the limited sample size and exclusion of infants with congenital anomalies.

Funding: None; Competing interests: None stated.

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