OBSTETRICS Placenta accreta: risk factors, perinatal outcomes, and consequences for subsequent births Tamar Eshkoli, MD; Adi Y. Weintraub, MD; Ruslan Sergienko, BA; Eyal Sheiner, MD, PhD OBJECTIVE: We sought to evaluate risk factors and perinatal outcomes of pregnancies complicated with placenta accreta and to study perinatal outcomes in subsequent pregnancies. STUDY DESIGN: A retrospective study comparing all singleton cesar- ean deliveries (CD) of women with and without placenta accreta was conducted. In addition, a retrospective comparison of all subsequent singleton CD of women with a previous placenta accreta, with CD of women with no such history, was performed during the years 1988 through 2011. Stratified analysis using multiple logistic regression models was performed to control for confounders. RESULTS: During the study period, there were 34,869 CD, of which 0.4% (n = 139) were complicated with placenta accreta. Using a mul- tivariable analysis with backward elimination, year of birth (adjusted odds ratio [aOR], 1.06; 95% confidence interval [CI], 1.03–1.09; P  .001), previous CD (aOR, 5.11; 95% CI, 3.42–7.65; P  .001), and placenta previa (aOR, 50.75; 95% CI, 35.57–72.45; P  .001) were found to be independently associated with placenta accreta. There were 30 subsequent pregnancies of women with placenta accreta. Re- current accreta occurred in 4 patients (13.3%). Previous placenta ac- creta was significantly associated with uterine rupture (3.3% vs 0.3%, P  .01) peripartum hysterectomy (3.3% vs 0.2%, P  .001), and the need for blood transfusions (16.7% vs 4%, P  .001). Nevertheless, increased risk for adverse perinatal outcomes such as low Apgar scores at 1 and 5 minutes and perinatal mortality was not found in these patients. CONCLUSION: Prior CD and placenta previa are independent risk factors for placenta accreta. A pregnancy following a previous placenta accreta is at increased risk for adverse maternal out- comes such as recurrent accreta, uterine rupture, and peripartum hysterectomy. However, adverse perinatal outcomes were not demonstrated. Key words: cesarean delivery, placenta accreta, placenta previa Cite this article as: Eshkoli T, Weintraub AY, Sergienko R, et al. Placenta accreta: risk factors, perinatal outcomes, and consequences for subsequent births. Am J Obstet Gynecol 2013;208:219.e1-7. P lacenta accreta occurs when the pla- cental implantation is abnormal: the decidua basalis that normally sepa- rates the anchoring placental villi and the myometrium is missing. 1 It is divided into 3 grades based on histopathology: placenta accreta where the chorionic villi are in contact with the myometrium, placenta increta where the chorionic villi invade the myometrium, and placenta percreta where the chorionic villi pene- trate the uterine serosa. 2 The exact pathogenesis is unknown. Possible etiologies include a mechanical factor (ie, primary deficiency of the de- cidua caused by local trauma to the uterine wall), a biological factor (ie, abnormal ma- ternal response to trophoblast invasion), or a combination of both processes. 1 Placenta accreta is considered a severe pregnancy complication that may be asso- ciated with massive and potentially life- threatening intrapartum and postpartum hemorrhage. 3 It has become a leading cause of emergency hysterectomy, ac- counting for 51.1% of emergency hyster- ectomies. 4,5 Maternal morbidity has been reported to occur in up to 60% and mor- tality in up to 7% of women with placenta accreta. In addition, the incidence of peri- natal complications is also increased mainly due to preterm birth and small-for- gestational-age fetuses. 6,7 The reported incidence of placenta ac- creta varies widely, mainly as a result of different diagnostic criteria. According to studies from the last 2 decades, the re- ported incidence has increased 10-fold. 1 Placenta accreta occurs in approximately 1:1000 deliveries with a reported range from 0.04% rising up to 0.9%. 3 The highest incidence (0.9%) was reported in a study based on clinical diagnostic cri- teria. 8 The increase in placenta accreta in recent years is attributed to the increase in the prevalence of known risk factors, particularly the increased number of caesarean deliveries (CD). 5 Several risk factors for placenta accreta have been reported. The most common and established being a previous CD. This is emphasized even more so in cases of pla- centa previa after a prior CD. 1 Increasing numbers of prior CD exponentially in- crease the risk of placenta accreta. 9,10 Ad- vanced maternal age is another significant independent risk factor. 9 In addition, mul- tiparity, previous uterine curettage, and previous uterine surgery (other than CD) were found to be risk factors in some stud- ies, but not in others. 11-13 Asherman syn- drome, smoking, and chronic hyperten- sion have also been implicated to be associated with placenta accreta. 14 Prior placenta accreta is probably a major risk factor, although scarce infor- From the Department of Obstetrics and Gynecology, Soroka University Medical Center (Drs Eshkoli, Weintraub, and Sheiner), and Ben-Gurion University of the Negev, Epidemiology and Health Services Evaluation (Mr Sergienko), Beer Sheva, Israel. Received Sept. 29, 2012; revised Dec. 14, 2012; accepted Dec. 31, 2012. The authors report no conflict of interest. Reprints: Tamar Eshkoli, MD. esh.tamar@gmail.com 0002-9378/$36.00 © 2013 Mosby, Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajog.2012.12.037 Research www. AJOG.org MARCH 2013 American Journal of Obstetrics & Gynecology 219.e1