Risk factors for placenta accreta

Objective: To identify risk factors associated with placenta accreta in a l arge cohort study. Methods: Data for this study came from the Taiwan Down Syndrome Screening G roup, an ongoing project on feasibility of serum screening in an Asian popu lation. Women who had serum screening for Down syndrome at 14-22 weeks' ges tation using alpha-fetoprotein (AFP) and free beta-hCG between January 1994 and June 1997, and delivered in the same institution, were included (n = 1 0,672). Those who had multiple gestations (n = 200), overt diabetes (n = 11 ), or fetal malformations (n = 101) were excluded. If a woman was involved more than once, one randomly selected pregnancy was included in the analysi s (n = 9349). Twenty-eight pregnancies were complicated by placenta accreta , diagnosed by clinical presentation (n = 26) or histologic confirmation (n = 2). Multiple logistic regression with adjustment for potentially confoun ding variables was used to identify independent risk factors for placenta a ccreta. Results: Women who had placenta previa (odds ratio [OR] 54.2; 95% confidenc e interval [CI] 17.8, 165.5) and second-trimester serum levels of AFP and f ree beta-hCG greater than 2.5 multiples of the median (OR 8.3; 95% CI 1.8, 39.3 and OR 3.9; 95% CI 1.5, 9.9, respectively), and were 35 years and olde r (OR 3.2; 95% CI 1.1, 9.4) were at increased risk of having placenta accre ta. Conclusion: Risk factors for placenta accreta include placenta previa, abno rmally elevated second-trimester AFP and free beta-hCG levels, and advanced maternal age. (Obstet Gynecol 1999;93:545-50. (C) 1999 by The American Col lege of Obstetricians and Gynecologists.).