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

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.