(783) Placental basal plate myofibers and risk of hypertensive disorders of pregnancy

Basal plate myofiber (BPMF) refers to the myometrial fibers attachment to the basal plate on placental pathology evaluation. The presence of BPMF may represent occult invasion of placenta or may reflect abnormal placental implantation in a prior pregnancy. It is possible that abnormalities in trophoblast biology associated with BPMF may also alter the physiologic transformation of the spiral arteries in these pregnancies. This study is designed to evaluate the association of BPMF with preeclampsia and gestational hypertension, which are conditions associated with abnormal spiral artery remodeling.

Study Design:

This retrospective cohort study was conducted at a single academic institution between 2012 and 2020. Participants with BPMF in placental histology report constituted our cases, and those without this finding were included as controls. Regression analysis was performed to evaluate the association of BPMF and these pregnancy complications adjusted for confounders including maternal age, parity, IVF, and chronic hypertension.

Results:

As shown in Table 1, total of 1,679 individuals were included; of which n=211 (12.6%) were cases and n=1,468 (87.4%) were controls. Older individuals and a greater number of pregnancies conceived by IVF were noted among cases. There were no significant differences in parity, mode of delivery or the frequency of chronic hypertension and prior cesarean sections between study groups. No significant differences in the rates of preeclampsia were noted between cases and controls (13.7% vs. 15.3%, P=0.552); however, a lower proportion of gestational hypertension was observed among cases compared to controls (7.9% vs 13.7%, P=0.025). The association of BPMF and gestational hypertension remained independent after adjusting for confounders (OR 0.495 [95% CI: 0.284, 0.861], P=0.013).

Conclusion: Our findings demonstrated that BPMF is independently associated with a lower risk of gestational hypertension. The rate of preeclampsia was also lower among individuals with BPMF findings in placental pathology; however, the differences did not reach statistical significance.