More than 10,000 preterm babies worldwide have been enrolled in trials evaluating probiotics administration for the prevention of necrotising enterocolitis, with very few adverse events reported. Despite this, probiotic safety is frequently cited as a concern when using this intervention. This review addresses why a preterm baby may be at risk when administered a live microbial product, short- and longer-term safety data in relation to probiotic use and regulatory aspects around probiotic manufacture and preparations. [ABSTRACT FROM AUTHOR]