OBJECTIVE We evaluated the published literature on the effectiveness of amnioinfusion in reducing meconium below the vocal cords and meconium aspiration syndrome among infants born to women presenting with more than trace meconium-stained fluid. METHODS A literature search was conducted to evaluate clinical trials of amnioinfusion and meconium aspiration. Trials meeting certain basic design criteria (n = 5), which included a prospective study design and blinded assessment of newborn outcome, were selected for statistical analyses estimating the average effect's size and direction. In total, 247 women with meconium-stained fluid receiving amnioinfusion and 260 women with meconium-stained fluid not receiving amnioinfusion were represented by these trials. RESULTS Infants born to women with meconium-stained fluid receiving amnioinfusion were less likely to have meconium below the vocal cords (odds ratio 0.13, 95% confidence interval 0.08 to 0.20) and were less likely to have meconium aspiration syndrome (odds ratio 0.20, 95% confidence interval 0.08 to 0.48) than were infants born to women with meconium-stained fluid not receiving amnioinfusion. CONCLUSIONS Amnioinfusion appears to be an effective intrauterine intervention for the prevention of meconium aspiration. Clinicians should consider implementing amnioinfusion in women presenting with thick meconium to prevent intrapartal meconium aspiration in newborns.