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

INTRODUCTION: The published evidence on the association between magnesium sulphate (MgSO4) and delayed passage of meconium (DPM) is contradictory. OBJECTIVES: 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. POPULATION AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.