Table 1.

The Robson classification. CS: cesarean section.

Robson Class	Description
1	Nulliparous women with a single cephalic pregnancy, ≥37 weeks gestation in spontaneous labor
2A	Nulliparous women with a single cephalic pregnancy, ≥37 weeks gestation who had labor induced
2B	Nulliparous women with a single cephalic pregnancy, ≥37 weeks gestation who were delivered by CS before labor
3	Multiparous women without a previous uterine scar, with a single cephalic pregnancy, ≥37 weeks gestation in spontaneous labor
4A	Multiparous women without a previous uterine scar, with a single cephalic pregnancy, ≥37 weeks gestation who had labor induced
4B	Multiparous women without a previous uterine scar, with a single cephalic pregnancy, ≥37 weeks gestation who were delivered by CS before labor
5	All multiparous women with at least one previous uterine scar, with a single cephalic pregnancy, ≥37 weeks gestation
6	All nulliparous women with a single breech presentation
7	All multiparous women with a single breech presentation, including women with a previous uterine scar
8	All women with multiple pregnancy, including women with a previous uterine scar
9	All women with a single pregnancy with a transverse or oblique lie, including women with a previous uterine scar
10	All women with a single cephalic pregnancy <37 weeks gestation, including women with a previous uterine scar