RECENT CHANGES IN DELIVERY SITE OF LOW-BIRTH-WEIGHT INFANTS IN WASHINGTON - IMPACT ON BIRTH WEIGHT-SPECIFIC MORTALITY

OBJECTIVES: Our purpose was to ascertain whether the proportion of low -birth-weight infants delivered in Washington at tertiary hospitals ch anged between 1980 and 1991 and whether mortality differed by level of birth hospital. STUDY DESIGN: A retrospective cohort study was perfor med of 500 to 2499 gm infants born to Washington residents between 198 0 and 1991 (n = 43,228). RESULTS: Overall, the percentage of low-birth -weight infants born at tertiary centers rose from 1980 to 1982 throug h 1986 to 1988 and subsequently declined significantly. Among infants weighing <2000 gm nontertiary delivery was associated with greater pot entially preventable mortality (500 to 999 gm, relative risk 1.5, 95% confidence interval 1.3 to 1.8; 1000 to 1499 gm, relative risk 2.1, 95 % confidence interval 1.3 to 3.3; 1500 to 1999 gm, relative risk 1.6, 95% confidence interval 1.0 to 2.6). Nontertiary delivery of 2000 to 2 499 gm infants was associated with lower overall mortality (relative r isk 0.5, 95% confidence interval 0.3 to 0.8), but higher-risk deliveri es in this birth weight range were apparently concentrated at tertiary hospitals. CONCLUSIONS: In light of the apparent benefit of tertiary center birth for infants weighing <2000 gm, the possible erosion of ef fective regionalized perinatal care networks should be monitored close ly.