Any breastfeeding, even for a few days, is better than none, but most authorities including the Department of Health now recommend that babies be exclusively breastfed for at least six months. The Department also recommends that that breastfeeding is continued, with the addition of appropriate weaning foods, for as long as the mother and baby want.
Breastfed babies have a lower chance of SIDS
As long ago as 1965 it was shown that babies under 3 months who died of SIDS were less likely to be breastfed than infants who did not die. Since then, numerous studies have supported the protective effects of breastfeeding, with one overview report concluding that breastfeeding reduces the incidence of SIDS by approximately half.
Even a brief period of breastfeeding can be protective for your baby. It has been shown that both partial and exclusive breastfeeding have been associated with a lower SIDS rate, but that exclusive breastfeeding was associated with the lowest risk.