Neonatal lupus erythematosus (NLE) develops in foetuses of mothers with Ro/SSA and La/SSB antibodies and may include foetal atrioventricular block and dermatologic manifestations. In this study, we investigated postnatal Ro and La IgG, IgA and IgM antibody levels up to 1 year of age in 32 children born to Ro/SSA positive mothers. Antibody levels were correlated with NLE manifestations, and the role of breast feeding in transfer of autoantibodies from mother to child was evaluated. Ro52, Ro60 and La IgG antibodies all transferred from the mothers to their foetus in utero and were present in the infant at birth as detected by enzyme-linked immunosorbent assay using recombinant antigens and a synthetic peptide. A significant decrease in Ro52, Ro60 and La IgG autoantibody levels of the infants was observed from birth to 4-5 weeks of age (P < 0.05, P < 0.05 and P < 0.01). Ro- and La-specific IgA and IgM antibodies were detected in the serum from a subset of mothers. However, Ro- and La-specific IgA and IgM antibody levels were low or non-detectable in children raised both with and without breastfeeding. Furthermore, NLE skin lesions developed independently of breastfeeding. Our findings support a role for placental materno-foetal transfer of IgG autoantibodies in the pathogenesis of NLE and indicate that refraining from breastfeeding does not protect from NLE skin involvement.