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Letters to the Editor

Re: “Completed Weeks of Gestation and Risk of Respiratory Syncytial Virus in Late Preterm Infants”

Sheridan-Pereira, Margaret FRCPI; Paes, Bosco FRCPC

Author Information
The Pediatric Infectious Disease Journal: December 2017 - Volume 36 - Issue 12 - p 1227-1228
doi: 10.1097/INF.0000000000001577
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To the Editors:

We thank Dr. Chabra for her comments. Dr. Chabra considers the respiratory syncytial virus preterm (32-36 completed weeks gestation) risk estimation measure for RSV hospitalization in Ireland (PREMI) study’s use of “32 and 36 completed weeks gestation” to represent infants “32 weeks and 0 days to 36 weeks and 6 days” “inaccurate” and “misleading,” contending that “36 weeks is completed at 36 weeks and 0 days and not at 36 weeks and 6 days.”1 However, the convention of truncating gestational age to “completed” weeks, which was adopted in 2011 for our study,1 for example, “a 25 week, 5 day fetus is considered 25 weeks gestational age (25 weeks and 0 days up to 25 weeks and 6 days),” has the imprimatur of the American Academy of Pediatrics2 (AAP) and several robust publications on birth standards.3,4

Dr. Chabra5,6 in her previous publications registers concerns and calls for a single “language” to communicate a specific contextual meaning concurrent with the World Health Organization (WHO). However, WHO supports the nomenclature that the thirty-seventh week of gestation signifies 36 completed weeks.7 Reaffirmation of the AAP policy8 regarding “completed weeks” indicates their prioritization of context over linguistic syntax, pragmatics or semantics. We concur with the AAP that newborn “gestational age” in completed weeks as defined in our study1 should be used instead of “menstrual age” to describe the age of the newborn infant.2,8

While we agree that the AAP8 or WHO recommendations7 pose a quandary regarding a generalizable definition of “completed weeks of gestation,” reaching universal consensus would involve changing how the nomenclature of neonatal gestational age is typically discussed in terms of completed weeks and revising standardized datasets that conform to our definition.2,3 From an obstetrical viewpoint, however the thirty-seventh week of pregnancy signifies 36 weeks, 0–6 days, but postnatally the infant will likely be recorded as 36 completed weeks.

Our study1 enrolled late and moderately preterm (32 weeks and 0 days to 33 weeks and 6 days) infants because moderately preterm babies were not routinely offered respiratory syncytial virus prophylaxis in Ireland. Dr. Chabra considered it “important to clarify” that late-preterm infants as defined by the WHO and National Institute of Child Health and Human Development should include babies born between 34 completed weeks (34 weeks and 0 days or day 239) and less than 37 completed weeks (36 weeks and 6 days or day 259). We acknowledge that the use of the “late-preterm” terminology in our study’s key words and running head was inappropriate and should have been correctly listed as “moderate and late-preterm infants” to reflect the total spectrum of enrolled subjects.1 However, late-preterms based on the WHO definition were incorporated under the broad veil of recruited “32–36 completed weeks gestational age” infants. Moreover, our study1 title is unambiguous and the entire data were correctly assembled based on clear, a priori definitions that were generalizable to all participating centers and can be replicated in other studies employing the same definition.1 In retrospect, modifying the abbreviated and running head titles of the study to comply with the journal’s character limits and incorporate “moderate and late-preterms” may have been a worthy pursuit.

Margaret Sheridan-Pereira, FRCPI
Department of Pediatrics and Newborn Medicine
Coombe Women and Infants University Hospital
Department of Pediatrics
Trinity College Dublin
Dublin, Ireland

Bosco Paes, FRCPC
Department of Pediatrics
McMaster University
Hamilton, Ontario, Canada

REFERENCES

1. Sheridan-Pereira M, Murphy J, Sloan J, et al. Respiratory syncytial virus preterm (32-36 completed weeks of gestation) risk estimation measure for RSV hospitalization in Ireland: a prospective study. Pediatr Infect Dis J. 2016;35:1924.
2. Engle WA; American Academy of Pediatrics Committee on Fetus and Newborn. Age terminology during the perinatal period. Pediatrics. 2004;114:13621364.
3. Barbier A, Boivin A, Yoon W, et al.; Canadian Neonatal Network. New reference curves for head circumference at birth, by gestational age. Pediatrics. 2013;131:e1158e1167.
4. Blidner IN, McClemont S, Anderson GD, et al. Size-at-birth standards for an urban Canadian population. Can Med Assoc J. 1984;130:133140.
5. Chabra S. Concept of gestational age in completed weeks: Lost in translation. Obstet Gynecol 2012;119:183184.
6. Chabra S. The enigma of 36 completed weeks of gestation: 36 0/7 or 36 6/7? J Women’s Health (Larchmt). 2014;23:437.
7. World Health Organization. ICD-10: International Statistical Classification of Diseases and Related Health Problems, Tenth Revision. 2010.Geneva: World Health Organization.
8. Engle WA; American Academy of Pediatrics Committee on Fetus and Newborn. Age terminology during the perinatal period. Pediatrics. 2004;114:13621364.
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