Abstract: Of twenty eligible studies, ten evaluated breastfeeding and ten evaluated supplemental breast milk. Sixteen studies analysed used heel lance and four used venepuncture as procedure. We noted marked heterogeneity in control intervention and pain assessment measures among the studies. Neonates in the breastfeeding group had statistically a significantly lower increase in heart rate, reduced proportion of crying time and reduced duration of first cry and total crying time compared to positioning (swaddled and placed in a crib), holding by mother, placebo, pacifier use, no intervention or oral sucrose group, or both. Premature Infant Pain Profile (PIPP) scores were significantly lower in the breastfeeding group compared to positioning, placebo or oral sucrose group, or both. However, there was no statistically significant difference in PIPP scores when compared to no intervention. Douleur Aigue Nouveau-ne scores (DAN) were significantly lower in the breastfeeding group compared to the placebo group and the group held in mother's arms, but not when compared to the glucose group. Neonatal Infant Pain Scale (NIPS) was significantly lower in the breastfeeding group compared to the no intervention group, but there was no difference when compared to the oral sucrose group. The Neonatal Facial Coding System (NFCS) was significantly lower in the breastfeeding group when compared to oral glucose, pacifier use, holding by mother and no intervention, but no difference was found when compared to formula feeding. Supplemental breast milk yielded variable results. Neonates in the supplemental breast milk group had a significantly lower increase in heart rate, a reduction in duration of crying and a lower NFCS compared to the placebo group. Neonates in the supplemental breast milk group had a significantly higher increase in heart rate changes when compared to the sucrose group. Sucrose (in any concentration, i.e. 12.5%, 20%, 25%) was found to reduce the duration of cry when compared to breast milk, as did glycine, pacifier use, rocking, or no intervention. Breast milk was found not to be effective in reducing validated and non-validated pain scores such as NIPS, NFCS, and DAN; only being significantly better when compared to placebo (water) or massage. We did not identify any study that has evaluated safety/effectiveness of repeated administration of breastfeeding or supplemental breast milk for pain relief. If available, breastfeeding or breast milk should be used to alleviate procedural pain in neonates undergoing a single painful procedure rather than placebo, positioning or no intervention. Administration of glucose/sucrose had similar effectiveness as breastfeeding for reducing pain. The effectiveness of breast milk for painful procedure should be studied in the preterm population, as there are currently a limited number of studies in the literature that have assessed it's effectiveness in this population.

Plain-language summary: Different studies done in babies have shown that breastfeeding is a good way to reduce the pain babies feel when subjected to minor painful procedures. These studies have been done in full-term babies and they have shown that breastfeeding is effective by demonstrating that it reduces babies' crying time and reduces different pain scores that have been validated for babies. Breast milk given by syringe has not shown the same efficacy as breastfeeding itself. No studies have been done in premature babies, and so new studies are needed to determine if the use of supplemental breast milk in these small babies is effective in reducing their pain.