P 23 Maternal vascular malperfusion in spontaneous preterm birth and outcome of subsequent pregnancy

INTRODUCTION Spontaneous preterm birth (SPTB) common complicates pregnancy. It has several causes and its pathophysiology has not yet been elucidated. In a significant proportion of SPTB, placental histology shows signs of maternal vascular malperfusion; these signs are commonly associated with hypertensive disorders of pregnancy (HD) or fetal growth restriction (FGR). Therefore, we hypothesized that women with a SPTB and signs of maternal vascular malperfusion in the placenta are at risk for HD and FGR in a subsequent pregnancy. OBJECTIVE The objective of this study was to describe the association between placental histology of SPTB and the incidence of HD and FGR in the subsequent pregnancy. MATERIALS AND METHODS We included women with a history of SPTB, and a subsequent ongoing pregnancy (n=110). Histological placental characteristics in the pregnancy complicated by SPTB were described according to new international guidelines, and related to the outcome of the subsequent pregnancy. RESULTS Delivery in the index pregnancy had a median gestational age of 27.7 weeks. In 61.8% (n=68) of the placentas signs of vascular malperfusion were observed. Maternal and respectively fetal inflammatory response was observed in 51.8 %(n=57) and 46.4% (n=51) and was observed as a secondary finding in 42.6% (n=29) and 36.8% (n=25) of the placentas with maternal vascular malperfusion. In the index pregnancy HD was present in 8.2% (n=9), and FGR in 10.9% (n=12). In the subsequent pregnancy HD was present in 12.7% (n=14) and FGR in 5.5 % (n=6). The incidence of HD or FGR in the subsequent pregnancy was not associated with histological signs of maternal vascular malperfusion in the index pregnancy. CONCLUSION Women with a history of SPTB have an elevated risk on hypertensive diseases in the subsequent pregnancy, when compared to epidemiologic data on the incidence of HD in women with a prior term birth. The incidence of HD was not associated with of the presence of placental maternal vascular malperfusion in the index pregnancy. This data suggest that signs of maternal vascular malperfusion by placental histology in SPTB cannot be used as a marker for adverse outcome in a subsequent pregnancy.