Table 1 Definition of stages and phases of labour and diagnostic criteria for dystocia for current sub-study [8–10].

First stage

From onset of regular contractions leading to cervical dilatation

Latent phase

Cervix dilatation 0 - 3.9 cm

Not given in this phase

Active phase

Cervix dilatation ≥ 4 cm

< 2 cm assessed over four hours

Second stage

From full dilatation of cervix until the baby is borne

Descending phase

From full dilatation of cervix to strong and irresistible urge to push

No descending ≥ 2 hours or ≥ 3 hours if epidural was administrated

Expulsive phase

Strong and irresistible pushing during the major part of the contractions

No progress ≥ 1 hour