Decidual and placental histologic findings in patients experiencing spontaneous abortions in relation to pregnancy order

Problem: In investigating possible immunologic causes of miscarriage, we hypothesized a more frequent maternal immune response in placental tissue in women miscarrying their first pregnancy, compared to woman miscarrying following at least one full-term delivery. Method of study: We reviewed the medical charts of 273 consecutive women who had treatment for miscarriage. After application of the exclusion criteria, 32 patients were selected who had a full-term pregnancy outcome following the index miscarriage. The patients were divided into two groups based on the pregnancy order of the index miscarriage. Group 1 (n = 16) included women who lost their first pregnancy. Group 2 (n = 16) included women who miscarried a pregnancy after at least one full-term delivery. Miscarriage tissue was evaluated for placental and decidual histologic features of uteroplacental vasculopathy and chronic inflammation. Results: Lesions of chronic inflammatory and uteroplacental vasculopathy were generally more common in Group 1 as compared to Group 2, and the presence of more than one of the histopathologic lesions was significantly more frequent in Group 1 (37.5%, 6/16) than in Group 2 (0/16, P = .02, Fisher's Exact). Conclusions: This study demonstrates more frequent lesions of chronic inflammation and uteroplacental vasculopathy in miscarriage patients with a first pregnancy loss, compared to those patients who have had a pregnancy loss following at least one full-term delivery.