Cervical dilatation at diagnosis of active phase of labour determines the mode of delivery and peripartum outcomes: a retrospective study in a single tertiary centre in Malaysia

BACKGROUND: There is an increasing trend of Caesarean section rate in Malaysia. Limited evidence demonstrated the benefits of changing the demarcation of the active phase of labour. METHODS: This was a retrospective study of 3980 singletons, term pregnancy, spontaneous labouring women between 2015 and 2019 comparing outcomes between those with cervical dilation of 4 versus 6 cm at diagnosis of the active phase of labour. RESULTS: A total of 3403 (85.5%) women had cervical dilatation of 4 cm, and 577 (14.5%) at 6 cm upon diagnosis of the active phase of labour. Women in 4 cm group were significantly heavier at delivery (p = 0.015) but significantly more multiparous women were in 6 cm group (p < 0.001). There were significantly fewer women in the 6 cm group who needed oxytocin infusion (p < 0.001) and epidural analgesia (p < 0.001) with significantly lower caesarean section rate (p < 0.001) done for fetal distress and poor progress (p < 0.001 both). The mean duration from diagnosis of the active phase of labour until delivery was significantly shorter in the 6 cm group (p < 0.001) with lighter mean birth weight (p = 0.019) and fewer neonates with arterial cord pH < 7.20 (p = 0.047) requiring neonatal intensive care unit admissions (p = 0.01). Multiparity (AOR = 0.488, p < 0.001), oxytocin augmentation (AOR = 0.487, p < 0.001) and active phase of labour diagnosed at 6 cm (AOR = 0.337, p < 0.001) reduced the risk of caesarean delivery. Caesarean delivery increased the risk of neonatal intensive care admission by 27% (AOR = 1.73, p < 0.001). CONCLUSIONS: Active phase of labour at 6 cm cervical dilatation is associated with reduced primary caesarean delivery rate, labour intervention, shorter labour duration and fewer neonatal complications.