DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY LETTER TO THE EDITOR
Subsets of preterm and term infants: call for consistency interminology
Shilpi ChabraDivision of Neonatology, University of Washington, Seattle, WA, USA.
Correspondence to: [email protected]
doi: 10.1111/dmcn.12126
SIR–In the recent article1 studying the patterns of func-tioning and predictive factors in children born moderatelypreterm or at term, the study cohort includes infantsdescribed by the authors as moderately preterm (gesta-tional age 32–36wks). The comparison group included 130children born at term (gestational age 38–41wks). It isimportant to note that the definition of moderately pre-term infants has been shifting over the past few years. Inthe National Center for Vital Statistics report includingthe final data for 2003, moderately preterm infants weredefined as infants of 32 to 36 weeks’ gestational age.2
In 2005, however, the National Institute of Child Healthand Human Development of the National Institutes ofHealth recommended a new terminology: late preterm, forinfants born between 34 and 37 completed weeks’ gesta-tional age (34–36wks 6d).3 By the most recent definition,moderately preterm infants include infants born between32 to 34 weeks’ gestational age (32–33wks 6d).4,5 In orderto clarify this concept, Figure 1 shows a visual plot of theweeks of gestation and definitions. Also, as regards of termgestation, the World Health Organization defines termbirth as childbirth occurring at 37 to 42 weeks’ gestationalage (37–41wks 6d) which is also endorsed by the AmericanAcademy of Pediatrics and the American College of Obste-tricians and Gynecologists. Cserjesi et al., however,describe term infants to include infants 38 to 41 weeks’gestational age in the comparison group of the study. It isunclear if infants born between 37 and 37 weeks 6 days’gestational age (which are term gestation by the definitionabove) were excluded from the comparison group. Thisgroup of infants represents a subset of term infants called‘early term’ infants and their exclusion from the termcohort would not be an accurate comparison.
In order to limit confusion in the ongoing researchregarding outcomes of moderately preterm and late-preterm infants, it is imperative for scientists to use stan-dardized definitions for the subsets of preterm (moderatelypreterm and late preterm) infants. Use of internationallyaccepted nomenclature is important to design future stud-ies which will help enhance our knowledge and add toevidence-based medicine. It is time to call for consistencyin terminology for the subset of preterm infants’ particu-larly moderately preterm infants and term infants, amongproviders all around the globe.
REFERENCES
1. Cserjesi R, Van Braeckel KN, Timmerman M, et al. Pat-
terns of functioning and predictive factors in children
born moderately preterm or at term. Dev Med Child Neu-
rol 2012; 54: 710–5.
2. Martin JA, Hamilton BE, Sutton PD, et al. Births: final
data for 2003. Natl Vital Stat Rep 2005; 54: 1–116.
3. Raju TN. Epidemiology of late preterm (near-term)
births. Clin Perinatol 2006; 33: 751–63.
4. Boyle EM. The late moderate preterm baby. Semin Fet
Neonat Med 2012; 17: 119.
5. Fawke J. What contributes to the outcomes of moderate and
late preterm birth?Dev Med Child Neurol 2012; 54: 676–7.
Week 33
Week 34
Week 35
Week 36
Week 37
< 320/7 weeks ofgestational age = VeryPreterm
320/7 – 326/7
330/7 – 336/7
340/7 – 346/7
350/7 – 356/7
360/7 – 366/7
> 370/7 weeks ofgestational age = Term
Moderately preterm
320/7- 336/7 weeks of
gestational age
Late preterm
340/7 - 366/7 weeks of
gestational age
Figure 1: Moderately preterm and late preterm infants.
© The Author. Developmental Medicine & Child Neurology © 2013 Mac Keith Press 673
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