Dr Iorio and colleagues describe the results of a retrospective analysis that examined the relationship between exclusive breastfeeding and postpartum relapses in 23 women followed up at their center. Their results are remarkably similar to those we described1 and actually support, rather than contradict, our overall conclusions. They found that women in the NBF group were twice as likely to relapse in the postpartum year and did so sooner than women in the BF group (proportions of women with relapses in NBF and BF groups, 53% vs 25%, respectively). Their results failed to achieve statistical significance, but this is simply owing to low study power. The belief that failure to achieve statistical significance is proof of no effect is a well-recognized statistical fallacy.2
Langer-Gould A. Protective Effect of Breastfeeding in Postpartum Relapse Rate of Mothers With Multiple Sclerosis—Reply. Arch Neurol. 2009;66(12):1580–1581. doi:10.1001/archneurol.2009.282
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