Lactate values during labour and their correlation with maternal and foetal outcome: a prospective observational single-centre study

Uterine contractions during labour are regulated by hormonal and metabolic processes, including oxytocin release, catecholamines modulation, and the hypoxia-induced force increase (HIFI) mechanism. This study investigates the relationship between lactate levels—produced during myometrial contraction and transient hypoxia—and maternal and foetal outcomes. In a cohort of 303 women receiving neuraxial analgesia, lactate was measured at three time points: at the time of diagnosis of the active phase of the first stage of labour (T0), at the beginning of active pushing (T1), and at delivery (T2). Lactate levels increased progressively, exceeding 2 mmol/L at T1 and T2. However, no significant correlation was found between lactate levels and postpartum haemorrhage or neonatal umbilical cord pH. Multiparous women exhibited lower lactate levels at T1 and T2 (p < 0.001), likely due to more efficient myometrial response and metabolic adaptation. Lactate, rather than solely indicating hypoxia, may act as an energy substrate. These findings suggest that lactate plays a physiological role in labour and should not be viewed exclusively as a marker of distress. Understanding its role could refine the clinical interpretation of maternal metabolic stress and improve labour management strategies.