Campbell-Yeo ML, Johnston CC, Joseph KS, Feeley N, Chambers CT, Barrington KJ: Cobedding and Recovery Time After Heel Lance in Preterm Twins: Results of a Randomized Trial. Pediatrics 2012. If I might be permitted a little self-promotion… this new study (which was certainly not my idea, and was accomplished as a result of the efforts of Marsha Campell-Yeo, certainly not mine) is, I think, of very high quality.
There is a lot of talk about Co-bedding of twins, but little reliable data about the effects, benefits or risks. This study was designed to see if co-bedding is analgesic. Now that may seem a strange objective, but we know that kangaroo care is analgesic, whether done by mothers or fathers (another study by Celeste Johnston, Marsha, and Francoise Filion). I thought that just the physical closeness of the other twin could have an effect, by the same mechanisms as kangaroo care, whatever they might be. So we randomized twins to be co-bedded or not, and then examined their responses to a heel prick that they needed for their medical care.
The primary outcome was not different between study groups, those co-bedded or not. We noted that the pain scores after heel stick were rather low, because all of the babies got sucrose, automated lancets, etc. So although both groups still had a small pain response to the heelstick, we were unable to show any effect of the co-bedding. The main secondary outcome, that is how quickly the babies settled back down to baseline after the intervention, was, in contrast, different between groups, the co-bedded babies recovered significantly more quickly.
The nice thing about this study was that the pain scores (PIPP the premature infant pain profile) increased to maximum that was quite low (average of about 7) suggesting only mild pain. So in a controlled situation, with the use of good technique and sucrose, pain can be reduced even when doing invasive procedures.
Similarly low scores were reported in another study now available on-line (also from Celeste Johnston and her collaborators) which showed that kangaroo care by mothers is slightly more analgesic than kangaroo care by non-related other women. As you might imagine they had a relatively low rate of consent from the mothers to do the study, I don’t know if they had any trouble getting the volunteers to be the alternate “kangaroos” but I don’t think the nurses in my unit would be too happy giving kangaroo care to the babies during their blood sampling! But maybe I’m wrong.