Dinoprostone pessaries (DP) are widely used for cervical ripening, and while licensed for 12-h administration in Australia, 24-h use is also reported. We examined 396 consecutive women before and after a protocol change from 12-h to 24-h DP use to determine whether extended DP use decreases the need for additional mechanical cervical ripening. No significant difference in cervical ripening balloon (CRB) requirement or vaginal birth rates was detected, showing that prolonged DP use does not reduce subsequent use of CRB.