Double-lined nomogram of cervical dilatation in Chinese primigravidas.

By studying normal labors in 500 Chinese primigravidae, a nomogram has been constructed to show the normal progression of cervical dilatation starting from cervical os of 3 cm dilatation. Paralleled 'alert' lines and 'action' lines were derived from this nomogram. Clinical evaluation of this double-lined nomogram showed that poor progression of cervical dilatation resulting in an abnormal outcome can be predicted at earlier stages. The use of this nomogram together with the partogram greatly improved the management of labor in the individual patient and the guidance of the labor ward as a whole.