825 There is widespread agreement that antiphospholipid antibodies are associated with pregnancy loss and throm- bosis. 1 Some investigators have also found that antiphos- pholipid antibodies are associated with preeclampsia, 2, 3 whereas others have not. 4, 5 Women with known risk fac- tors for preeclampsia have not been studied. The utility of screening for antiphospholipid antibodies among women at risk for recurrent preeclampsia is therefore uncertain. From the Department of Obstetrics and Gynecology, University of Utah a ; the Department of Obstetrics and Gynecology, University of Pittsburgh b ; the Department of Obstetrics and Gynecology, University of Tennessee, Memphis c ; the Department of Obstetrics and Gynecology, The University of Alabama, Birmingham d ; the Department of Obstetrics and Gynecol- ogy, University of Chicago e ; the Department of Obstetrics and Gynecology, Medical University of South Carolina f ; the Department of Obstetrics and Gynecology, The Ohio State University g ; the Department of Obstet- rics and Gynecology, University of Southern California h ; the Depart- ment of Obstetrics and Gynecology, University of Cincinnati i ; the De- partment of Obstetrics and Gynecology, Bowman Gray School of Medicine j ; the Department of Obstetrics and Gynecology, University of Oklahoma k ; the National Institute of Child Health and Human Devel- opment l ; and the George Washington University Biostatistics Center. m Other members of the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network and their partici- pating institutions are listed at the end of the article. Supported by the H.A. and Edna Benning Foundation and grants from the National Institute of Child Health and Human Development (HD19897, HD21410, HD21414, HD21434, HD27860, HD27861, HD27869, HD27883, HD27889, HD27905, HD27915, HD27917). Presented at the Nineteenth Annual Meeting of the American Gynecolog- ical and Obstetrical Society, Williamsburg, Virginia, September 7-9, 2000. Reprint requests: D. Ware Branch, MD, Room 2B200 Medical Center, 50 N Medical Dr, Salt Lake City, UT 84132. 6/6/113846 doi:10.1067/mob.2001.113846 Antiphospholipid antibodies in women at risk for preeclampsia D. Ware Branch, MD, a T. Flint Porter, MD, a Linda Rittenhouse, BS, a Steve Caritis, MD, b Baha Sibai, MD, c Barbara Hogg, MD, d Marshall D. Lindheimer, MD, e Mark Klebanoff, MD, l Cora MacPherson, PhD, m J. Peter VanDorsten, MD, f Mark Landon, MD, g Richard Paul, MD, h Menachem Miodovnik, MD, i Paul Meis, MD, j and Gary Thurnau, MD, k for the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network Salt Lake City, Utah, Pittsburgh, Pennsylvania, Memphis, Tennessee, Birmingham, Alabama, Chicago, Illinois, Charleston, South Carolina, Columbus and Cincinnati, Ohio, Los Angeles, California, Winston-Salem, North Carolina, Oklahoma City, Oklahoma, Bethesda, Maryland, and Washington, D.C. OBJECTIVE: The aim of this study was to determine whether positive results of tests for any of 5 antiphos- pholipid antibodies are associated with recurrent preeclampsia among women with a history of preeclampsia in a previous pregnancy. STUDY DESIGN: Second-trimester serum samples were obtained from 317 women with preeclampsia in a previous pregnancy who were being followed up in a prospective treatment trial. The serum samples were measured by enzyme-linked immunoassay for immunoglobulin G and immunoglobulin M antibodies against 5 phospholipids. Positive results were analyzed with regard to preeclampsia, severe preeclampsia, intrauterine growth restriction, and preterm delivery. RESULTS: Sixty-two of the 317 women (20%) had recurrent preeclampsia develop, 19 (6%) had severe pre- eclampsia, and 18 (5.8%) were delivered of infants with growth restriction. Positive results of tests for im- munoglobulin G or immunoglobulin M antiphospholipid antibodies were not associated with recurrent pre- eclampsia. Positive results for immunoglobulin G or immunoglobulin M antibodies at the 99th percentile were also not associated with preterm delivery.Positive results at the 99th percentile for immunoglobulin G an- tiphosphatidylserine antibody were associated with severe preeclampsia, and positive results at the 99th per- centile for immunoglobulin G anticardiolipin, antiphosphatidylinositol, and antiphosphatidylglycerol antibodies were associated with intrauterine growth restriction. The positive predictive values for these outcomes all were approximately 30%. CONCLUSION: Positive results of testing for antiphospholipid antibodies in the second trimester were not associated with recurrent preeclampsia among women at risk because of a history of preeclampsia. Positive results for immunoglobulin G antiphosphatidylserine antibody were associated with severe preeclampsia, and positive results for immunoglobulin G anticardiolipin, antiphosphatidylinositol, and antiphosphatidylglyc- erol antibodies were associated with intrauterine growth restriction.However, the positive predictive values for all these associations were modest.Testing for antiphospholipid antibodies during pregnancy is of little prognostic value in the assessment of the risk for recurrent preeclampsia among women with a history of preeclampsia. (Am J Obstet Gynecol 2001;184:825-34.) Key words: Anticardiolipin antibodies, antiphospholipid antibodies, intrauterine growth restriction, preeclampsia