The present study of 466 consecutive liveborn preterm singleton deliveries included 238 cases of spontaneous preterm labor and delivery, 175 cases with premature rupture of membranes, 13 cases of nonhypertensive abruption, 18 cases of preeclampsia, and 22 cases of placenta previa. Placental infarction, chronic villitis, and decidual pathologic processes showed different associations with fetal growth, depending on the clinical circumstances. Placental infarction was associated with decreased growth in all groups except placenta previa; in cases of placenta previa, placental infarction was associated with heavier infants. Chronic villitis was related to decreased growth in spontaneous rupture of membranes and preterm labor cases but was related to increased growth in cases of preeclampsia.