When does external cephalic version succeed?

From 1984 to 1987, 300 pregnant women with fetal malpresentations underwent an attempt at external cephalic version (ECV) during the last trimester. A consecutive analysis of factors associated with successful version was performed during this period. The final version rate after one or more attempts was 58%, being lower in nulliparous (39%) than in parous women (80%). Multivariate analyses (logistic regression) identified only three significant variables out of 16 with independent power to explain successful version. The overall most important factor was parity (p less than 0.001), followed by fetal presentation (p less than 0.001) and amount of amniotic fluid (p = 0.019).