The relation between ease of forceps delivery and speed of cervical dilatation.

An attempt has been made to predict a difficult forceps delivery. The duration of the 7 to 10 cm cervical dilatation interval was measured from the completed cervimetric chart in 952 consecutive patients who delivered spontaneously between December 1973 and September 1974. The 7 to 10 cm cervical dilatation intervals of this group were compared with those of 378 consecutive patients in whom forceps were applied with the fetal head in the occipito-anterior position and 83 consecutive patients where Kielland's forceps rotation from the occipito-tranverse or occipito-posterior position was performed. The forceps deliveries were graded as 'easy', 'moderately difficult', or 'difficult'. In only 5% of the spontaneous delivery group did the 7 to 10 cm cervical dilatation interval exceed two hours. In the occipito-anterior and Kielland's forceps groups an 'easy' delivery could be expected if the 7 to 10 cm cervical dilatation interval was less than two hours. The greater this interval increased beyond two hours, the greater was the proportion of 'moderately difficult' and 'difficult' forceps deliveries.