Original article
Neurosensory Disabilities at School Age in Geographic Cohorts of Extremely Low Birth Weight Children Born Between the 1970s and the 1990s

https://doi.org/10.1016/j.jpeds.2008.12.036Get rights and content

Objective

To contrast the rates of neurosensory disabilities at age 8 years in extremely low birth weight (ELBW; birth weight 500 to 999 g) children born in the state of Victoria, Australia in 4 four distinct eras from the late 1970s to the late 1990s.

Study design

Study subjects were assessed at age 8 years. Results were compared among 4 ELBW cohorts (87 of 89 children born in 1979-1980, 206 of 212 born in 1985-1987, 224 of 241 born in 1991-1992, and 160 of 170 born in 1997), and between each of these ELBW cohorts and normal birth weight (NBW; birth weight > 2499 g) controls.

Results

The survival rate for ELBW children rose from 25% for the 1979-1980 cohort to 73% for the 1997 cohort. No statistically significant differences in the disability rates were seen in the 4 eras; however, in the 1997 cohort, disability rates were significantly higher in the ELBW children compared with NBW controls: mild disability, 36.7% vs 9.8%; moderate disability, 10.1% vs 2.3%; and severe disability, 8.2% vs 0.6%.

Conclusions

The survival rate of ELBW children continues to rise over time. Despite this, however, the rates of disability in these vulnerable children at school age have remained stable and high relative to controls.

Section snippets

ELBW Births in 1997

The ELBW cohort born between January 1 and December 31, 1997 in Victoria, Australia comprised 170 survivors to age 8 years out of 233 consecutive live births with birth weight 500 to 999 g, a survival rate of 73.0%. The corresponding NBW cohort comprised 199 randomly selected children of birth weight > 2499 g born in 1 of the 3 level-III perinatal centers in Victoria, all of whom survived to age 8 years. Controls were born on the expected date of birth of an ELBW child, matched for sex and

Results

The ELBW children born in 1997 had a survival rate of 73% at age 8; the follow-up rates for survivors at age 8 were 94% for the ELBW children and 87% (173/199) for the NBW controls (Table I). No statistically significant differences in cognitive or motor development at age 2 years, as assessed using the Bayley Scales of Infant Development, Second Edition,18 were seen between the controls who were evaluated and those who were not evaluated at age 8 years (P = .97 and .32, respectively). The

Discussion

The rate of survival to age 8 years in ELBW children born in Victoria rose progressively over the 4 eras studied. This increase was especially dramatic in those children with a birth weight of 500 to 749 g. Our findings are consistent with trends reported in other developed countries20 and confirm our first 2 study hypotheses. The rates of disabilities in ELBW children remained stable over time and were higher than those in NBW controls in the 1997 cohort, as were the differences between ELBW

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  • Cited by (0)

    Supported by the Department of Human Services, Victoria, Australia.

    The authors declare no potential conflicts of interest, real or perceived.

    A complete list of Victorian Infant Collaborative Study Group members is available at www.jpeds.com (Appendix).

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