Maternal vascular malperfusion in spontaneous preterm birth placentas related to clinical outcome of subsequent pregnancy

Introduction Spontaneous preterm birth (SPTB) has several causes and its pathophysiology remains unclear. In a significant proportion of SPTB, placental histology shows signs of maternal vascular malperfusion (MVM); commonly associated with hypertensive disorders of pregnancy (HD), fetal growth restriction (FGR) and placental abruption, together referred to as clinical ischemic placental diseases (IPD). We hypothesized that women with SPTB and placental MVM are at elevated risk for IPD in a subsequent pregnancy. Methods We included women with SPTB in our cohort and followed the subsequent ongoing pregnancy (n = 110). Histological placental characteristics in the index were reported according to new international guidelines, and related to the clinical outcome of the subsequent pregnancy. Results In the SPTB placentas, we observed MVM in 61.8% (n = 68). In the subsequent pregnancies in 19.1% (n = 21) at least one clinical sign of IPD was present (HD (12.7%), FGR (5.5%) or placental abruption (0.9%)). There was no significant difference in the prevalence of clinical IPD or recurrence of SPTB in the subsequent pregnancy between women with and without placental MVM in the index pregnancy, although our study was not powered to detect small differences. Discussion Women with a history of SPTB have an elevated risk of IPD in the subsequent pregnancy. MVM is present in a large proportion of SPTB placentas. The presence of placental MVM in the index pregnancy does not predict clinical IPD or recurrent SPTB in a subsequent pregnancy.