Abstract
Objective: Pregnancy complications such as intra-amniotic infection, preeclampsia, and fetal intrauterine growth restriction (IUGR) account for most cases of preterm birth (PTB), but many spontaneous PTB cases do not have a clear etiology. We hypothesize that placental insufficiency may be a potential cause of idiopathic PTB.
Methods: Secondary analysis of 82 placental samples from women with PTB obtained from a multicenter trial of repeat versus single antenatal corticosteroids. Samples were centrally reviewed by a single placental pathologist masked to clinical outcomes. The histopathologic criterion for infection was the presence of acute chorioamnionitis defined as neutrophils marginating into the chorionic plate. Placental villous hypermaturation (PVH) was defined as a predominance of terminal villi (similar to term placenta) with extensive syncytial knotting. Idiopathic PTB comprised a group without another known etiology such as preeclampsia, IUGR or infection.
Results: Acute chorioamnionitis was observed in 33/82 (40%) cases. Other known causes of PTB were reported in 18/82 (22%). The remaining 31/82 (38%) were idiopathic. The frequency of PVH in idiopathic PTB (26/31 = 84%) was similar to cases with IUGR or preeclampsia (16/18 = 89%), but significantly more common than PVH in the group with acute chorioamnionitis (10/33 = 30%) (p < 0.001).
Conclusions: PVH, which is a histologic marker of relative placental insufficiency, is a common finding in idiopathic PTB.
Acknowledgements
We are very grateful for the diligence and organization provided by Dr Michael Varner (Ob/Gyn, University of Utah), Dr Kenneth Ward (Juneau Biosciences, Utah) and Lesa Nelson (Taueret Laboratories, Utah) to maintain the tissue bank from the NICHD Maternal-Fetal Medicine Units (MFMU) Network antenatal corticosteroids trial for our study. We also wish to thank the following subcommittee members who participated in protocol development and coordination between clinical research centers (Michelle DiVito, MSN and Francee Johnson, RN, BSN), protocol/data management and statistical analysis (Elizabeth Thom, Ph.D.). In addition to the authors, other members of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network are as follows:
Drexel University – M. DiVito, A. Sciscione, V. Berghella, M. Pollock, M. Talucci
Wayne State University – M. Dombrowski, G. Norman, A. Millinder, C. Sudz, D. Driscoll
The Ohio State University – F. Johnson, J. Iams, M. Landon, S. Meadows, P. Shubert
University of Utah – M. Varner, K. Anderson, A. Guzman, A. Crowley, M. Fuller
Northwestern University – G. Mallett
University of Texas Southwestern Medical Center – K. Leveno, D. Weightman, L. Fay-Randall, P. Mesa
Wake Forest University Health Sciences – M. Harper, P. Meis, M. Swain, C. Moorefield
University of Pittsburgh – S. Caritis, T. Kamon, K. Lain, M. Cotroneo
Columbia University – M. Miodovnik, F. Malone, V. Pemberton, S. Bousleiman
Case Western Reserve University–MetroHealth Medical Center – P. Catalano, C. Milluzzi, C. Santori
University of North Carolina at Chapel Hill – K. Moise, K. Dorman
University of Chicago – A. Moawad, P. Jones, G. Mallett
University of Miami – D. Martin, F. Doyle
The University of Texas Health Science Center at Houston – L. Gilstrap, M.C. Day
Brown University – M. Carpenter, D. Allard, J. Tillinghast
University of Alabama at Birmingham – A. Northen, K. Bailey
University of Cincinnati – M. Miodovnik, H. How, N. Elder, B. Alexander, W. Girdler
University of Tennessee – B. Mabie, R. Ramsey
Eunice Kennedy Shriver National Institute of Child Health and Human Development – D. McNellis, K. Howell, S. Tolivaisa
The George Washington University Biostatistics Center – E.Thom, F. Galbis-Reig, L. Leuchtenburg MFMU Network Steering Committee Chair (Vanderbilt University Medical Center) — S. Gabbe
Declaration of Interest
The authors report no declarations of interest other than the following finanacial support. Dr Morgan was funded by the Office of Research on Women’s Health and the Eunice Kennedy Shriver National Institute of Child Health and Human Development, Oregon BIRCWH: HD043488-08. This research was also supported by grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) [HD21410, HD21414, HD27869, HD27917, HD27905, HD27860, HD27861, HD27915, HD34122, HD34116, HD34208, HD34136, HD40500, HD40485, HD40544, HD40545, HD40560, HD40512, HD36801] and M01-RR-000080 from the National Center for Research Resources (NCRR) and its content is solely the responsibility of the authors and does not necessarily represent the official views of the NICHD, the National Institutes of Health and the NCRR.