• The prevalence of exclusive breastfeeding for three month old infants between groups randomised to pacifier and no pacifier exposure. Pacifier introduction is delayed until 15 days to ensure that breastfeeding is firmly established. [ Time Frame: Three months ] [ Designated as safety issue: No ]
  

• To evaluate the effects of the pacifier's introduction when breastfeeding is firmly established at 15 days on the duration of breastfeeding [ Time Frame: one year ] [ Designated as safety issue: No ]
  
• To evaluate the median breastfeeding duration in months in relation to the frequency of pacifier use [ Time Frame: one year ] [ Designated as safety issue: No ]
  
• To test whether pacifier use is causally related with muguet, otitis and sore nipples [ Time Frame: one year ] [ Designated as safety issue: No ]
  
• Compliance with group assignment [ Time Frame: one year ] [ Designated as safety issue: No ]
  

The incidence of Sudden infant death syndrome in developing countries is comparable with that of developed countries. Two important risk factors with implications for prevention are prone sleeping position and the association with smoke. Also, breastfeeding has been reported to be protective against SIDS. In accordance with WHO/UNICEF recommendations, lactation consultants and other health professionals within "Baby-Friendly" institutions typically discourage the use of pacifiers in breastfed infants. The recent American Academy of Pediatrics policy statement, however, recommends pacifier use, during periods of sleep as a potential method to reduce the risk of SIDS. Previous observational studies had been unanimous in reporting an approximate doubling of the risk of early weaning with daily pacifier use. However, randomized controlled trials in developed countries, have not shown that giving pacifiers results in shorter breastfeeding duration, except when pacifiers are given in the first 5 days. It has therefore been seen that practically every author of a major study on the association between breastfeeding and pacifier use has proposed that the question can only be fully and completely answered by randomized studies. To date there are no large randomized studies evaluating the influence of pacifier use on breastfeeding duration. Our Primary outcome is to compare the prevalence of exclusive breastfeeding at three months in infants between groups randomised to pacifier and no pacifier exposure once breastfeedings have been fully established. Second outcome: to evaluate the effects of the pacifier's introduction when breastfeeding is firmly established at 15 days on the duration of breastfeeding. Recruitment to the trial will take place in several public and private hospitals.

Those mothers who do not show a strong preference in regards to the introduction of the pacifier, will be randomised during the postpartum visit at 2 weeks (if well established breastfeeding is present) on two arms:

1. No pacifier,
2. Pacifier introduced at 15 days.

Structured telephone interviews will be conducted at 1, 2, 3, 4, 5, and 6 months and every 60 days thereafter until the breastfeeding has ended to record breastfeeding duration and type (exclusive or not) and pacifier use.