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Antecedents of Abnormally Invasive Placenta in Primiparous Women: Risk Associated With Gynecologic Procedures

Baldwin, Heather, J., PhD; Patterson, Jillian, A., MBiostat; Nippita, Tanya, A., FRANZCOG; Torvaldsen, Siranda, MAppEpid, PhD; Ibiebele, Ibinabo, MIPH, PhD; Simpson, Judy, M., PhD; Ford, Jane, B., PhD

doi: 10.1097/AOG.0000000000002434
Contents: Original Research

OBJECTIVE: To evaluate the association between prior invasive gynecologic procedures and the risk of subsequent abnormally invasive placenta (ie, placenta accreta, increta, and percreta).

METHODS: We conducted a population-based data linkage study including all primiparous women who delivered in New South Wales, Australia, between 2003 and 2012. Data were obtained from linked birth and hospital admissions with a minimum lookback period of 2 years. Prior procedures invasive of the uterus were considered including gynecologic laparoscopy with instrumentation of the uterus; hysteroscopy, including operative hysteroscopy; curettage, including suction curettage and surgical termination; and endometrial ablation. Modified Poisson regression was used to determine the association between the number of prior gynecologic procedures and risk of abnormally invasive placenta.

RESULTS: Eight hundred fifty-four cases of abnormally invasive placenta were identified among 380,775 deliveries included in the study (22.4/10,000). In total, 33,296 primiparous women had at least one prior procedure (8.7%). Among women with abnormally invasive placenta, 152 (17.8%) had undergone at least one procedure compared with 33,144 (8.7%) among women without abnormally invasive placenta (P<.01). After adjustment, the relative risk was 1.5 for one procedure (99% CI 1.1–1.9), 2.7 for two procedures (99% CI 1.7–4.4), and 5.1 for three or more procedures (99% CI 2.7–9.6). Abnormally invasive placenta was also positively associated with maternal age, socioeconomic advantage, mother being Australia-born, placenta previa, hypertension, multiple births, use of assisted reproductive technology, and female fetal sex.

CONCLUSION: Women with a history of prior invasive gynecologic procedures were more likely to develop abnormally invasive placenta. These insights may be used to inform management of pregnancies in women with a history of gynecologic procedures.

Primiparous women with a history of invasive uterine procedures have an increased risk of abnormally invasive placenta, and the risk increases with number of prior procedures.

Clinical and Population Perinatal Health Research, Kolling Institute, Northern Sydney Local Health District, St. Leonards, New South Wales, the Biostatistics Training Program, New South Wales Ministry of Health, North Sydney, Sydney Medical School Northern, University of Sydney, New South Wales, the Department of Obstetrics and Gynaecology, Royal North Shore Hospital, St. Leonards, New South Wales, the School of Public Health and Community Medicine, UNSW Sydney, New South Wales, and the Sydney School of Public Health, University of Sydney, New South Wales, Australia.

Corresponding author: Heather J. Baldwin, PhD, New South Wales Ministry of Health, 73 Miller Street, North Sydney, 2065, NSW, Australia; email:

Funded by National Health and Medical Research Council grants (#1001066, #1094822). Heather J. Baldwin and Siranda Torvaldsen were funded through a New South Wales (NSW) Ministry of Health Population Health and Health Services Research Support Program grant. Jane B. Ford is supported by an ARC Future Fellowship (#FT120100069). Heather J. Baldwin is supported by the NSW Biostatistics Training Program.

Financial Disclosure The authors did not report any potential conflicts of interest.

The authors thank the NSW Ministry of Health for access to the population health data and the NSW Centre for Health Record Linkage for linking the data sets.

Each author has indicated that he or she has met the journal's requirements for authorship.

© 2018 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.