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Am J Perinatol 2005; 22(5): 279-286
DOI: 10.1055/s-2005-870899
Copyright © 2005 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA.

Fetal and Neonatal Mortality Among Twin Gestations in a Canadian Population: The Effect of Intrapair Birthweight Discordance

Shi Wu Wen1 , 2 , 3 , Karen Fung Kee Fung2 , Ling Huang1 , Kitaw Demissie4 , K. S. Joseph5 , Alexander C. Allen5 , Michael S. Kramer6 , for the Fetal and Infant Health Study Group[*] of the Canadian Perinatal Surveillance System
  • 1Health Surveillance and Epidemiology Division, Centre for Healthy Human Development, Health Canada, Ottawa, Ontario, Canada
  • 2Department of Obstetrics and Gynecology, Faculty of Medicine, and the University of Ottawa, Ottawa, Ontario, Canada
  • 3Clinical Epidemiology Program, University of Ottawa, Ottawa, Ontario, Canada
  • 4Division of Epidemiology, University of Medicine and Dentistry of New Jersey, School of Public Health, Piscataway, New Jersey
  • 5Perinatal Epidemiology Research Unit, Departments of Obstetrics and Gynecology and of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
  • 6Departments of Pediatrics and of Epidemiology and Biostatistics, McGill University, Montreal, Quebec, Canada
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Publication History

Publication Date:
15 June 2005 (online)

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ABSTRACT

The purpose of this study was to examine the association between intrapair birthweight discordance and fetal and neonatal mortality. This was a historical cohort study, using the Statistics Canada linked birth-infant death file. Twin births in Canada (excluding Ontario) for the period 1986-1997 were studied.

Outcome measures were fetal and neonatal mortality. Among 59,034 twin births, 53% had 0 to 9% birthweight difference; 30% had 10 to 19% discordance; 11% had 20 to 29% discordance; and 6% had ≥ 30% discordance. Maternal age, parity, sex discordance, and gestational age were important factors affecting birth weight discordance. Fetal death rates were 0.95, 1.26, 3.14, and 11.10%, respectively, in infants with a birthweight discordance of 0 to 9, 10 to 19, 20 to 29, and ≥ 30%. Corresponding figures for neonatal death rates were 1.90, 2.32, 3.05, and 8.86%, respectively. Adjustment for important confounding variables including the actual birthweight and gestational age substantially reduced the birthweight discordance-related risk of fetal and neonatal mortality, but the results remained statistically significant and clinically important. The birthweight discordance-related risk of fetal and neonatal mortality was higher in smaller twins than in larger twins and higher in infants with gestational age ≥ 37 weeks than those < 37 weeks. Birthweight discordance is an important risk factor for fetal and neonatal mortality, and the birthweight discordance-related risk of fetal and neonatal mortality is higher in smaller twins than in larger twins and higher in term twins than in preterm twins.

KEYWORDS

Twins - birthweight discordance - fetal death - infant death - Canada

REFERENCES

7 Contributing members: Margaret Cyr (Statistics Canada), Martha Fair (Statistics Canada), Arne Ohlsson (University of Toronto), I.D. Rusen (Health Canada).

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 Dr.
Shi Wu Wen

The Ottawa Hospital, General Campus, 501 Smyth Road

Box 241, Ottawa, Ontario, Canada