Skip to main content
PMC home page
CMAJ : Canadian Medical Association Journal logoLink to CMAJ : Canadian Medical Association Journal
. 1996 Oct 15;155(8):1047–1052.

Recent trends in Canadian infant mortality rates: effect of changes in registration of live newborns weighing less than 500 g.

K S Joseph 1, M S Kramer 1
PMCID: PMC1335353  PMID: 8873632

Abstract

OBJECTIVE: To ascertain whether the increase in the crude infant mortality rate in Canada in 1993 was due to a recent increase in the registration of newborns weighing less than 500 g as live births. DESIGN: Ecological study, with Poisson regression analysis. SETTING: Canada. SUBJECTS: All live births and infant deaths in Canada between 1987 and 1993, as reported by Statistics Canada. Data from Newfoundland were excluded because they were incomplete for 4 years. OUTCOME MEASURES: Proportion of live births by low-birth-weight category; and annual crude and adjusted infant mortality rates. RESULTS: Over the study period the proportion of newborns weighing less than 500 g registered as live births increased significantly (chi 2 for trend = 71.26, p < 0.01). This trend was an isolated phenomenon rather than a general increase in all low-birth-weight categories (chi 2 for trend in the proportion of newborns weighing 500 to 2400 g registered as live births = 1.14, p = 0.28). The crude infant mortality rate per 1000 live births decreased from 6.4 in 1991 to 6.1 in 1992 and then increased to 6.3 in 1993. Poisson regression analysis revealed that the apparent increase in the infant mortality rate was caused by the increased registration of infants weighing less than 500 g as live births. The adjusted infant mortality estimate for 1993 was lower than that for 1992. CONCLUSIONS: The increased infant mortality rate in Canada in 1993 appears to be due to increased registration of infants weighing less than 500 g as live births. Comparisons of infant mortality rates by place and time should be adjusted for the proportion of such live births, especially if the comparisons involve recent years.

Full text

PDF
1047

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Cartlidge P. H., Stewart J. H. Effect of changing the stillbirth definition on evaluation of perinatal mortality rates. Lancet. 1995 Aug 19;346(8973):486–488. doi: 10.1016/s0140-6736(95)91327-0. [DOI] [PubMed] [Google Scholar]
  2. Doornbos J. P., Nordbeck H. J., Treffers P. E. The reliability of perinatal mortality statistics in The Netherlands. Am J Obstet Gynecol. 1987 May;156(5):1183–1187. doi: 10.1016/0002-9378(87)90138-4. [DOI] [PubMed] [Google Scholar]
  3. Fenton A. C., Field D. J., Mason E., Clarke M. Attitudes to viability of preterm infants and their effect on figures for perinatal mortality. BMJ. 1990 Feb 17;300(6722):434–436. doi: 10.1136/bmj.300.6722.434. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Greenland S., Robins J. Invited commentary: ecologic studies--biases, misconceptions, and counterexamples. Am J Epidemiol. 1994 Apr 15;139(8):747–760. doi: 10.1093/oxfordjournals.aje.a117069. [DOI] [PubMed] [Google Scholar]
  5. Howell E. M., Blondel B. International infant mortality rates: bias from reporting differences. Am J Public Health. 1994 May;84(5):850–852. doi: 10.2105/ajph.84.5.850. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Keirse M. J. Perinatal mortality rates do not contain what they purport to contain. Lancet. 1984 May 26;1(8387):1166–1169. doi: 10.1016/s0140-6736(84)91405-3. [DOI] [PubMed] [Google Scholar]
  7. Miettinen O. Estimability and estimation in case-referent studies. Am J Epidemiol. 1976 Feb;103(2):226–235. doi: 10.1093/oxfordjournals.aje.a112220. [DOI] [PubMed] [Google Scholar]
  8. Milner R. D., Beard R. W. Limit of fetal viability. Lancet. 1984 May 12;1(8385):1079–1080. doi: 10.1016/s0140-6736(84)91488-0. [DOI] [PubMed] [Google Scholar]
  9. Sachs B. P., Fretts R. C., Gardner R., Hellerstein S., Wampler N. S., Wise P. H. The impact of extreme prematurity and congenital anomalies on the interpretation of international comparisons of infant mortality. Obstet Gynecol. 1995 Jun;85(6):941–946. doi: 10.1016/0029-7844(95)00056-W. [DOI] [PubMed] [Google Scholar]
  10. Sepkowitz S. International rankings of infant mortality and the United States' vital statistics natality data collecting system--failure and success. Int J Epidemiol. 1995 Jun;24(3):583–588. doi: 10.1093/ije/24.3.583. [DOI] [PubMed] [Google Scholar]

Articles from CMAJ: Canadian Medical Association Journal are provided here courtesy of Canadian Medical Association

RESOURCES