To test the hypothesis that breast-feeding increases the risk of postpartum flare in inflammatory polyarthritis.
We compared disease activity during pregnancy and at 6 months postpartum among 49 non-breast-feeders, 38 first-time breast-feeders, and 50 repeat breast-feeders.
After we adjusted for possible confounders, including treatment, first-time breast-feeders had increased disease activity 6 months postpartum, based on self-reported symptoms, joint counts, and C-reactive protein levels.
Postpartum flare may be induced by breast-feeding.