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There are two interesting studies on breast milk as an analgesic (pain reliever) in this month’s issue of Pediatrics. Each compares the effects of breast milk to those of oral sugar (either glucose or sucrose) for relieving pain during the ubiquitous neonatal heel stick procedure.
The first study looked at late preterm infants (gestational age 34-36 weeks), and measured pain as indicated by crying and pain response (evaluated using the Premature Infant Pain Profile [PIPP] scale) [1]. All infants were being breastfed and were fed at least an hour before the procedure. They were randomized into two groups, one of which received expressed breast milk (from the infant’s mother) and one of which received a solution of glucose. (Glucose is a type of sugar; it’s exceedingly common in nature and in food, but is only about 70% as sweet as table sugar. Sugar solutions have been well established as a method of delivering pain relief to neonates [2]). The researchers found that infants given glucose displayed significantly less discomfort during and after the procedure compared to those given expressed breast milk. Interesting though these results are, they don’t particularly excite me. They can be taken to mean oral glucose is a superior analgesic to oral breast milk in late preterm newborns, but they can’t be taken to mean oral glucose is a superior analgesic to breastfeeding in late preterm newborns. This is because breastfeeding consists of more than simply oral administration of breast milk.
I’m more interested in the findings of a second study, also conducted on late preterm infants undergoing heel stick [3]. In this study, breastfed infants were randomized to one of three conditions: oral sucrose (table sugar) solution, expressed breast milk, or breastfeeding. Infants were fed or given sucrose during the heel stick procedure. Those being breastfed were held in their mother’s arms, while those receiving expressed breast milk or sucrose were held by a nurse. As in the first study, the researchers measured crying and pain response via PIPP. There was no significant difference in PIPP score for infants receiving breast milk versus those receiving sucrose. Interestingly enough, this was true for both the expressed breast milk group AND the group being breastfed. I have to admit to being surprised by the results; I would have guessed that there would be no difference between sucrose and expressed breast milk (or possibly that sucrose would be more effective), but that breastfeeding would provide superior analgesia!
Note that these results apply only to neonates (and, to be rigorous, only to late preterm neonates). It’s entirely possible that the establishment of a solid breastfeeding relationship over the course of the first weeks or months of life would change the relative efficacy of sugar solution versus expressed breast milk versus breastfeeding as analgesics (follow-up post on this issue forthcoming).
One final note — in the discussion portion of the second study (where the researchers talk about what their results mean and what they noticed while doing the study), there was a line that jumped out at me. The researchers were apparently, like me, surprised that they didn’t discover that breast milk was a superior analgesic. They suggested that one reason could have been that preterm infants have an “immature competence for sucking,” which could have reduced their ability to take enough milk to make a difference. Further, they noted (and this is what caught my eye), “We observed that these [preterm] newborns are more easily annoyed than term neonates…” Alrighty then!
Science Bottom Line:* In late preterm newborns, sugar solutions provide pain relief for procedures such as a heel lance. Breast milk, either expressed or obtained via breastfeeding, may provide similar pain relief, though some evidence suggests that breast milk is not as effective as sugar.
Do you think breast milk helps relieve pain?
References:
1) Bueno et al. Breast milk and glucose for pain relief in preterm infants: a noninferiority randomized controlled trial. Pediatrics. 2012 Apr;129(4):664-70. Epub 2012 Mar 5.
2) Harrison et al. Efficacy of sweet solutions for analgesia in infants between 1 and 12 months of age: a systematic review. Arch Dis Child. 2010 Jun;95(6):406-13. Epub 2010 May 12.
3) Simonse et al. Analgesic effect of breast milk versus sucrose for analgesia during heel lance in late preterm infants. Pediatrics. 2012 Apr;129(4):657-63. Epub 2012 Mar 5.