Features：
1. Consists of 6 cervical change and birth canal change module
2. It can show the dilation of the cervix, the change of the cervix canal and the relationship between the fetal head and
the ischial spine
3. Changes in various parts during the expansion period
Stage 1: no dilation of cervix, cervical canal does not efface, the position relation between fetal head and plane of
ischial, spine-5
Stage 2: dilation of 2cm of cervix, 50% effacement of cervical canal, position relation between fetal head and plane of
ischial spine-4
Stage 3: dilation of 4cm of cervix, full effacement of cervical canal, position relation between fetal head and plane of
ischial spine-3
Stage 4: dilation of 5cm of cervix,
full effacement of cervical canal,
position relationship between
fetal head and plane of ischial spine-0
Stage 5: dilation of 7cm of cervix, full
effacement of cervical canal, position
relation between fetal head and plane
of ischial spine+2
Stage 6: dilation of 10 cm of cervix, full
effacement of cervical canal, position
relation between fetal head and plane
of ischial spine+5