An international randomized controlled trial of amnioinfusion for thickly meconium stained amniotic fluid

Abstract

To determine if amnioinfusion (AI) for thickly meconium stained amniotic fluid reduces (1) perinatal death and/or moderate to severe meconium aspiration syndrome (primary outcome measure), (2) cesarean section, (3) other indicators of serious neonatal and maternal morbidity. In 56 centres in 13 countries, 1998 laboring women at ≥36 weeks gestation with thickly meconium stained liquor were stratified according to the presence or absence of variable fetal heart rate decelerations and randomized either to standard care or to AI, consisting of a transcervical bolus of 800 mL saline over 40 minutes, followed by infusion of 2 mL/minute to a maximum of 1500 mL. The composite primary outcome measure included perinatal death and/or severe or moderate meconium aspiration syndrome (MAS) based on clinical respiratory distress (severe: requiring mechanical ventilation; moderate: requiring oxygen supplementation at a FiO2 ≥ 40% or of ≥48 hours duration) as blindly adjudicated by a group of 3 neonatologists. Perinatal death and/or moderate or severe MAS occurred in 44 (4.5%) babies in the amnioinfusion group and 34 (3.4%) babies in the control group (RR = 1.3, 95% CI = 0.8-2.0). There was a trend toward more frequent cesarean delivery in the AI group (32% vs 29%; RR = 1.1; 95% CI 1.0-1.3). The distribution of other indicators of severe neonatal morbidity including arterial cord pH < 7.05 and severe maternal morbidity were similar in the two treatment groups. We found no evidence of heterogeneity of treatment effect, either across stratum as defined above, or across centres. For women in labor with thickly meconium stained amniotic fluid, amnioinfusion does not reduce the risk of meconium aspiration syndrome, cesarean delivery, or other major indicators of maternal or neonatal morbidity.