Antenatal magnesium sulphate and delayed passage of meconium: A multicentre study

The published evidence on the association between magnesium sulphate (MgSO₄) and delayed passage of meconium (DPM) is contradictory.

To determine whether there is an association between the administration of MgSO₄ to the mother and DPM in the neonate, and to analyse serum magnesium levels in neonates in relation to the cumulative dose of MgSO₄ administered to the mother.

Retrospective and prospective descriptive and analytical study conducted in patients delivered at or before 32 weeks of gestation in 2 tertiary care hospitals. Delayed passage of meconium was defined as failure to pass meconium within 48 h of birth and/or need for rectal stimulation on 2 or more occasions to pass stool and/or interval of at least 48 h between the first and second bowel movements.

The study included 283 patients (204 retrospectively and 79 prospectively), of who 152 (53.7%) experienced DPM. Delayed passage of meconium was not associated with antenatal MgSO₄ administration, the cumulative maternal MgSO4 dose or neonatal serum magnesium levels. Older gestational age (OR, 0.8; confidence interval [CI], 0.69-0.93; P = 0.003) was an independent protective factor against DPM, while the need for advanced resuscitation (OR, 2.24; CI 1.04-4.86; P = 0.04) was a risk factor for DPM.

The neonatal serum levels of magnesium reached with the doses of MgSO₄ administered to mothers were not associated with DPM. Lower gestational age and the need for advanced resuscitation were predictors associated with an increased risk of DPM.