Intrapartum amniotic fluid index and its relationship to fetal distress

Amniotic fluid index was measured in 50 consecutive laboring women after membrane rupture. The 10th percentile of the normal range was 6.2 cm. Thirty-three women had a repeat measurement by a second observer. Although there was no systematic bias between the two observers, the limits of agreement were wide: 95% of the measurements by one observer were between 0.59 and 2.07 times those of the second. Closer agreement was observed when amniotic fluid index was low (less than 6.2 cm). The relationship between intrapartum amniotic fluid index and fetal distress was then investigated in a further 60 laboring women. When compared with women with a normal intrapartum amniotic fluid index, women with a low amniotic fluid index had higher incidences of fetal heart rate abnormalities during the first stage of labor (64% vs 20%, p less than 0.01), meconium (grade II or III) at delivery (64% vs 35%, p less than 0.05), and operative delivery for fetal distress (57% vs 17%, p less than 0.01). Umbilical artery pH and Apgar scores were, however, similar for the two groups. Measurement of intrapartum amniotic fluid index may be an appropriate method for selecting women suitable for intrapartum aminoinfusion.