The failure to pass meconium in the first 24 h in a term baby is a significant symptom and should prompt a search for the underlying cause.
In a preterm baby, however, failure to open the bowels is not uncommon
After prematurity, the most common organic cause of constipation in the first weeks of life is Hirschsprung disease and this must be excluded by rectal examination followed by suction biopsy in all term infants when constipation follows on failure to pass meconium within the first 48 h.
Hirschsprung disease has an incidence of 1 in 5000 live births, and has complex inheritance; multiple genes have been found to be involved.
Neonatal constipation should always be taken seriously; failure to open the bowels at least every other day is outside the range of normality.
Intermittent suppositories are occasionally successful but more usually infants will need a stool softener (lactulose 2.5 ml b.d.) for a period of time to regularize the bowel habit.
Impaction, if present, must be relieved before a regular bowel habit is restored.