This article reviews retmspedive data derived from Sharp The BMPlace, San Diego for 1993-94 and from the University of California, Irvine. Bi&Gng Center for 1994 and compares these Endings to data obtained from the National Birth Center Study (NBC3 The focus of this article is on intrapartum transfer rates from the two freestanding birth centers as a critical clinii indicator. Cause-specific lmnsfer rates were calculated for eight diical conditions. Data suggest that cause-specific intrapartum transfer rates are influenced by factors such as risk profile. of the client population, distance to the referral center and mechanisms of transfer, debitions and diagnostic crikria used. and dinical practice guidelines. Reports from the literature. such as NBCS data, might serve as points of reference. but are likely not appropriate baseline indiitors (benchmarks of "best practice") for clinical events, against which individual perfommnce can be measured; rather. these benchmarks should be indiddy defined. based on chamcteristics unique to each birth center. 8 1997 by the Americar: Wlege of NurseMidwives. The birth center movement in the United States is a relatively recent trend. The Childbearing Center, the first out-of-hospital birth center of the modem-era alternative bii movement, was established in New York City in 1975 under the auspices of Maternity Center Association (1). ln 1994. 11,787 infants (0.2996 of all births in the United States) were born in a free&a&ing birth center (2). In the spring of 1995.135 centers were known to be established in the United States (3).
Early small-sample, single site reports of the outcomes of births in out+f-hospital settings helped to refine the usefulness of center-defined admission eligibility (lowrisk) criteria and to demonstrate the safety of alternative bii centers (4-7). The rarer. Large-scale. multisite studies (8,9) confirmed these data. The National Bii Center Study (NBCS) ( ) is the largest pmspective study of these birth setthgs reported to date. The Nf3CS and other studies offer ,a point of reference for the discussion of critical clinicd in$cators of the quality of care provided in birth centers.
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