American Journal of Epidemiology Vol. 134, No. 6: 604-613
Copyright © 1991 by The Johns Hopkins University School of Hygiene and Public Health
research-article |
Very Low Birth Weight: A Problematic Cohort for Epidemiologic Studies of Very Small or Immature Neonates
1Department of Epidemiology and Biostatistics, McGill University Montreal, Quebec, Canada
2Department of Pediatrics, McGill University Montreal, Quebec, Canada
3Department of Obstetrics and Gynecology, McGill University Montreal, Quebec, Canada
Reprint requests to Dr. Cody C Arnold, Cook-Fort Worth Children's Medical Center, 801 Seventh Avenue, Fort Worth, TX 76104
Despite widespread acceptance of the concept of very low birth weight (VLBW), i.e., birth weight of 
1,500 g, VLBW infants represent an extremely heterogeneous group of newborns, including those with very immature gestational age and those who are more mature but extremely growth retarded. To demonstrate how use of the VLBW rubric can lead to confounding bias that is not only large in magnitude but impossible to control satisfactorily, the authors divided 640 consecutive live neonates born in the Royal Victoria Hospital, Montreal, Canada, from 1978 to 1987 into two overlapping groups: a VLBW cohort (birth weight, 500–1500 g; n = 573) and a gestational age cohort (gestational age, 23–30 completed weeks; n = 466). Variation in growth status by gestational age was much more uniform in the 23- to 30-week cohort. Thus, although mean birth weight was similar in the 500- to 1,500-g and 23- to 30-week cohorts (1,055 vs. 1,064 g), the 500- to 1,500-g cohort was more mature (mean gestational age, 28.8 vs. 27.8 weeks; upper range, 39.7 vs. 30.9 weeks) and had twice the rate of intrauterine growth retardation (25.7 vs. 11.5%). These differences in maturity and growth resulted in a misleading protective effect of intrauterine growth retardation against in-hospital death in the 500- to 1,500-g cohort (crude odds ratio = 0.55 (95% confidence interval 0.36–0.83)) and a greater discrepancy in maturity between cesarean- and vaginally delivered infants (3.1 vs. 1. 5 weeks) in the 500- to 1,500-g vs. 23- to 30-week cohorts. These differences arise from inextricable confounding of growth status and maturity in the 500- to 1,500-g cohort, the most mature infants also being the most growth retarded. The removal of well-grown infants with birth weights of >1,500 g from the VLBW cohort leads to a progressively distorted spectrum of growth with advancing gestational age and an artifactual blunting of the beneficial effects of increasing maturity. The authors suggest that whenever fetal growth is an important exposure, outcome, or confounding variable, epidemiologic studies of extremely small or immature newborns should be based on gestational age rather than the VLBW criterion. Am J Epidemiol 1991;134:604-13.
birth weight; fetal growth retardation; infant; low birth weight; infant mortality; infant; premature
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  O. Dammann, B. Shah, M. Naples, F. Bednarek, J. Zupancic, E. N. Allred, A. Leviton, and for the ELGAN Study Investigators Interinstitutional Variation in Prediction of Death by SNAP-II and SNAPPE-II Among Extremely Preterm Infants Pediatrics, November 1, 2009; 124(5): e1001 - e1006. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Laughon, M. T. O'Shea, E. N. Allred, C. Bose, K. Kuban, L. J. Van Marter, R. A. Ehrenkranz, A. Leviton, and for the ELGAN Study Investigators Chronic Lung Disease and Developmental Delay at 2 Years of Age in Children Born Before 28 Weeks' Gestation Pediatrics, August 1, 2009; 124(2): 637 - 648. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. C. K. Kuban, E. N. Allred, T. M. O'Shea, N. Paneth, M. Pagano, O. Dammann, A. Leviton, A. Du Plessis, S. J. Westra, C. R. Miller, et al. Cranial Ultrasound Lesions in the NICU Predict Cerebral Palsy at Age 2 Years in Children Born at Extremely Low Gestational Age J Child Neurol, January 1, 2009; 24(1): 63 - 72. [Abstract] [PDF]
|
|
|
|
|
|
T. M. O'Shea, K. C. K. Kuban, E. N. Allred, N. Paneth, M. Pagano, O. Dammann, L. Bostic, K. Brooklier, S. Butler, D. J. Goldstein, et al. Neonatal Cranial Ultrasound Lesions and Developmental Delays at 2 Years of Age Among Extremely Low Gestational Age Children Pediatrics, September 1, 2008; 122(3): e662 - e669. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. H. Malloy Impact of Cesarean Section on Neonatal Mortality Rates Among Very Preterm Infants in the United States, 2000-2003 Pediatrics, August 1, 2008; 122(2): 285 - 292. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. A. Hutcheon and R. W. Platt The Missing Data Problem in Birth Weight Percentiles and Thresholds for "Small-for-Gestational-Age" Am. J. Epidemiol., April 1, 2008; 167(7): 786 - 792. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Sun, M. Vestergaard, C. B. Pedersen, J. Christensen, O. Basso, and J. Olsen Gestational Age, Birth Weight, Intrauterine Growth, and the Risk of Epilepsy Am. J. Epidemiol., February 1, 2008; 167(3): 262 - 270. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Arnaud, L. Daubisse-Marliac, M. White-Koning, V. Pierrat, B. Larroque, H. Grandjean, C. Alberge, S. Marret, A. Burguet, P.-Y. Ancel, et al. Prevalence and Associated Factors of Minor Neuromotor Dysfunctions at Age 5 Years in Prematurely Born Children: The EPIPAGE Study Arch Pediatr Adolesc Med, November 1, 2007; 161(11): 1053 - 1061. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. B Bartels, F. Schwab, C. Geffers, C. F Poets, and P. Gastmeier Nosocomial infection in small for gestational age newborns with birth weight <1500 g: a multicentre analysis Arch. Dis. Child. Fetal Neonatal Ed., November 1, 2007; 92(6): F449 - F453. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Laughon, C. Bose, E. Allred, T. M. O'Shea, L. J. V. Marter, F. Bednarek, A. Leviton, and for the ELGAN Study Investigators Factors Associated With Treatment for Hypotension in Extremely Low Gestational Age Newborns During the First Postnatal Week Pediatrics, February 1, 2007; 119(2): 273 - 280. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N Evans, J Hutchinson, J M Simpson, D Donoghue, B Darlow, D Henderson-Smart, and on behalf of the Australian and New Zealand Neonat Prenatal predictors of mortality in very preterm infants cared for in the Australian and New Zealand Neonatal Network Arch. Dis. Child. Fetal Neonatal Ed., January 1, 2007; 92(1): F34 - F40. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. J. Vincer, A. C. Allen, K. S. Joseph, D. A. Stinson, H. Scott, and E. Wood Increasing Prevalence of Cerebral Palsy Among Very Preterm Infants: A Population-Based Study Pediatrics, December 1, 2006; 118(6): e1621 - e1626. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Farooqi, B. Hagglof, G. Sedin, L. Gothefors, and F. Serenius Growth in 10- to 12-Year-Old Children Born at 23 to 25 Weeks' Gestation in the 1990s: A Swedish National Prospective Follow-up Study Pediatrics, November 1, 2006; 118(5): e1452 - e1465. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. H. Whitaker, J. F. Feldman, J. M. Lorenz, S. Shen, F. McNicholas, M. Nieto, D. McCulloch, J. A. Pinto-Martin, and N. Paneth Motor and cognitive outcomes in nondisabled low-birth-weight adolescents: early determinants. Arch Pediatr Adolesc Med, October 1, 2006; 160(10): 1040 - 1046. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. M. Kamoji, J. S. Dorling, B. N. Manktelow, E. S. Draper, and D. J. Field Extremely Growth-Retarded Infants: Is There a Viability Centile? Pediatrics, August 1, 2006; 118(2): 758 - 763. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. B. Bartels, D. Wypij, P. Wenzlaff, O. Dammann, and C. F. Poets Hospital volume and neonatal mortality among very low birth weight infants. Pediatrics, June 1, 2006; 117(6): 2206 - 2214. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P.-Y. Ancel, F. Livinec, B. Larroque, S. Marret, C. Arnaud, V. Pierrat, M. Dehan, S. N'Guyen, B. Escande, A. Burguet, et al. Cerebral Palsy Among Very Preterm Children in Relation to Gestational Age and Neonatal Ultrasound Abnormalities: The EPIPAGE Cohort Study Pediatrics, March 1, 2006; 117(3): 828 - 835. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D J Henderson-Smart, J L Hutchinson, D A Donoghue, N J Evans, J M Simpson, I Wright, and for the Australian and New Zealand Neonatal Networ Prenatal predictors of chronic lung disease in very preterm infants Arch. Dis. Child. Fetal Neonatal Ed., January 1, 2006; 91(1): F40 - F45. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. A. Darlow, D. J. Henderson-Smart, J. M. Simpson, and N. J. Evans Risk Factors for Severe Retinopathy of Prematurity Among Very Preterm Infants: A Unit-Based or Population-Based Approach?: In Reply Pediatrics, August 1, 2005; 116(2): 516 - 517. [Full Text] [PDF]
|
|
|
|
|
|
D B Bartels, L Kreienbrock, O Dammann, P Wenzlaff, and C F Poets Population based study on the outcome of small for gestational age newborns Arch. Dis. Child. Fetal Neonatal Ed., January 1, 2005; 90(1): F53 - F59. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N S Wood, K Costeloe, A T Gibson, E M Hennessy, N Marlow, and A R Wilkinson The EPICure study: growth and associated problems in children born at 25 weeks of gestational age or less Arch. Dis. Child. Fetal Neonatal Ed., November 1, 2003; 88(6): F492 - 500. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. E. Olsen, D. K. Richardson, C. H. Schmid, L. M. Ausman, and J. T. Dwyer Intersite Differences in Weight Growth Velocity of Extremely Premature Infants Pediatrics, December 1, 2002; 110(6): 1125 - 1132. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. MacDonald and Committee on Fetus and Newborn Perinatal Care at the Threshold of Viability Pediatrics, November 1, 2002; 110(5): 1024 - 1027. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. S. Wood, N. Marlow, K. Costeloe, A. T. Gibson, A. R. Wilkinson, and The EPICure Study Group Neurologic and Developmental Disability after Extremely Preterm Birth N. Engl. J. Med., August 10, 2000; 343(6): 378 - 384. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. H. Whitaker, R. Van Rossem, J. F. Feldman, I. S. Schonfeld, J. A. Pinto-Martin, C. Torre, D. Shaffer, and N. Paneth Psychiatrie Outcomes in Low-Birth-Weight Children at Age 6 Years: Relation to Neonatal Cranial Ultrasound Abnormalities Arch Gen Psychiatry, September 1, 1997; 54(9): 847 - 856. [Abstract] [PDF]
|
|
|
|
|
|
A. Leviton, N. Paneth, M. Susser, M. L. Reuss, E. N. Allred, K. Kuban, U. Sanocka, T. Hegyi, M. Hiatt, F. Shahrivar, et al. Maternal Receipt of Magnesium Sulfate Does Not Seem to Reduce the Risk of Neonatal White Matter Damage Pediatrics, April 1, 1997; 99(4): e2 - e2. [Abstract] [Full Text] [PDF]
|
|