Infants born at the threshold of viability in relation to neonatal mortality: Colorado, 1991 to 2003

Abstract

Objective-To determine the contribution of infants born at the threshold of viability (defined as <750 g birth weight) and the role of regionalization of perinatal care on the neonatal mortality rate (NMR) in Colorado. Result-The overall unadjusted NMR of the two time periods was 4.3 and 4.4 per 1000 live births, respectively (P=0.42). The contribution of infants with birth weights <750 g to the overall NMR increased from 45.0 to 54.5% (P<0.01). The odds of death for infants <750 g increased between time periods (Odd ratio 1.3, 95% Confidence interval 1.11, 1.61). However, NMR decreased between time periods for all birth weight categories, until infants <600 g. With respect to regionalization, the number of infants <750 g born in a level III care center increased slightly between the two time periods (69.6 versus 73.3%; P=0.04); however, adjusted analysis showed no difference in the practice of regionalization between time periods. Regardless of time period, infants who weighed <750 g born in a level III center had 60% lower mortality risk when compared to <750 g infants born in a non-level III center (P<0.01; 95% CI 0.30, 0.52).Conclusion-Despite advances in neonatal medicine, the overall NMR in the state of Colorado remained unchanged between the time periods of 1991 to 1996 and 1997 to 2003. Infants at the threshold of viability continue to have a large impact on the Colorado NMR, making up a larger proportion of overall neonatal deaths. While the results demonstrate that the risk of mortality is significantly reduced for <750 g infants born in a level III center, the practice of regionalization has not changed between the two time periods. Improved efforts to standardize the referral practices to ensure delivery of <750 g infants in level III centers could potentially reduce the impact of these infants on the NMR. While the overall NMR in Colorado has not changed between the two time periods, the NMR for infants >600 g has significantly decreased, suggesting that the

Perinatal Regionalization for Very Low-Birth-Weight and Very Preterm Infants

“…Studies that controlled more extensively (adjusting for maternal/perinatal risk factors and/or infant illness severity) 13,15,16,22,29 did not show significant evidence of heterogeneity (n = 5 studies; Q=7.60; P=.06) (Figure 3).…”

“…Unadjusted pooled incidence rates were calculated from reported birth and death counts at compared hospital levels. Four studies [13][14][15][16] did not provide level-specific death/birth counts and are excluded from these estimates.…”

“…Included data combine reported birth date interval strata (1980-1984, 1985-1989, and 1990-1994) and birth weight strata (500-1000 g and 1001-1500 g). c Raw death counts are not reported in Cifuentes et al 13 and Kamath et al 16 and are not stratified by hospital level in Howell et al 15 These studies are not included in combined death/birth counts.…”

“…To explore the possibility of differences in effect of hospital level at birth for the smallest VLBW infants, data from 5 studies 16,18,29,32,37 that reported birth weight-stratified data or that restricted study population to extremely low-birth-weight (Յ1000 g) infants were combined (n = 13 093). Extremely low-birth-weight infants born in non-level III hospitals had an …”

Response to Dr Garg and Dr Gogia

“…The data of Kamath et al 2 reflect the survival pattern of developed countries, USA and Western Europe. Our editorial commented on the influence of increased survival at threshold of viability in developed and developing countries that are striving to provide modern neonatal care and support thereby pushing the limits of viability.…”