Basal Plate Myofibers and the Risk of Placenta Accreta Spectrum in the Subsequent Pregnancy: A Large Single-Center Cohort

Abstract

Objective: We aimed to evaluate whether there is a significant association between a placental pathology diagnosis basal plate myofibers (BPMF) in an index pregnancy with PAS in the subsequent pregnancy. Study design: We conducted a retrospective nested cohort study of all cases with a histopathologic finding of BPMF between August 2012 and March 2020 at a single tertiary referral center. Data were collected for all subjects (cases and controls) with at least two consecutive pregnancies (the initial index pregnancy and at least one subsequent pregnancy) accompanied by a concomitant record of histopathologic study of the placenta at our center. The primary outcome was pathologically confirmed PAS in the subsequent pregnancy. Data are presented as percentage or median, interquartile range (IQR) accordingly. Results: A total of n=1,344 participants were included, of which n=119 (index cases) carried a contemporaneous histopathologic diagnosis of BPMF during the index pregnancy and n=1,225 did not (index controls). Among the index cases, patients with BPMF were older (31.0 [20, 42] vs 29.0 [15, 43], p <0.001), more likely to have undergone IVF for conception (10.9% vs 3.8%, p=0.001) and were of a more advanced gestational age at delivery (39.0 [25, 41] vs 38.0 [20, 42], p=0.006). In the subsequent pregnancy, the rate of PAS was significantly higher among the BPMF index cases (6.7% versus 1.1%, p<0.001). After adjusting for maternal age and IVF, a histopathologic diagnosis of BPMF in an index pregnancy was shown to be a significant risk factor for PAS in the subsequent gestation (HR 5.67 [95% CI: 2.28, 14.06], p <0.001). Conclusion: Our findings support that a histopathologic diagnosis of BPMF is an independent risk factor for PAS in the subsequent pregnancy.