Time To First Passage Of Meconium And Associated Factors In 800 Irish-Born Term Infants: A Real-Time Observational Study

ObjectivesTo develop an updated reference range for time to first passage of meconium in healthy, term, Irish-born infants and to determine associated obstetric and neonatal factors. DesignA real-time observational study, conducted on the postnatal ward, to record the precise time of infants first passage of meconium. Associated obstetric and neonatal factors were analysed. Maternal consent was obtained prior to delivery. Frequency, percentages and median [IQR] values were reported. Non-parametric tests Mann Whitney U, Kruskall Wallis and Spearman Correlation, and Chi Square test and Fishers exact test were performed. SettingLevel four, tertiary referral obstetric department PatientsHealthy, term newborns. Main outcome measuresTime to first passage of meconium, and obstetric and neonatal associations. ResultsIn 800 infant subjects the median [IQR] time to first passage of meconium is 6.00 [9.45] hours (range 0-82.8 hours); 98.1% passed meconium within the first 24 hours. There was a statistically significant negative weak correlation between time to first passage of meconium and gestation, and between time to first passage of meconium and birth weight. Mean rank [median] time to first passage of meconium was greater and statistically significant for elective versus emergency caesarean section. ConclusionsNinety-eight percent of Irish-born newborns pass meconium in the first 24 hours. Meconium passage is influenced by gestation at delivery, birth weight, and emergency versus elective caesarean section. Key MessagesO_ST_ABSWhat is already known on this topicC_ST_ABSMost healthy infants will pass meconium within 24 to 48 hours of delivery. Up-to-date data are limited and heterogenous. What this study addsDespite changes in obstetric practice, most term healthy infants will pass meconium by 24 hours. Time to first passage of meconium is influenced by gestation and birth weight, and for those delivered by emergency versus elective caesarean section. How this study might affect research, practice or policyIn the setting of modern obstetric care, infants who have not passed meconium by 24 hours should be clinically evaluated. Gestation and birth weight may be taken into account when assessing the timing of meconium passage.