We performed a prospective randomized study of saline solution amnioinfusion in four types of pregnancy complications: postterm pregnancy, variable decelerations in labor, preterm labor, and oligohydramnios-suspected growth retardation. A total of 100 patients were randomized, 43 to undergo amnioinfusion and 57 to be in a control group. Patients undergoing amnioinfusion had a significantly decreased incidence of postpartum endometritis (2.4% vs 19%, p = 0.01) and a lower incidence of cesarean delivery that was due to fetal distress in labor (4.7% vs 16%, p = 0.07). The use of amnioinfusion also made a significant contribution to the four-quadrant ultrasonographic estimate of amniotic fluid volume (14.7 vs 9.8 cm, p < 0.001). All other maternal and neonatal outcome parameters were similar between the two groups. We conclude that saline solution amnioinfusion in labor may be a beneficial procedure but that further studies are needed. © 1990.