RESUMO
OBJECTIVE: The objective of this study was to investigate the association between use of silicone nipple shields in the maternity ward and exclusive breastfeeding interruption in the first 6 months of the infant's life. DESIGN: Cohort study. SETTING: Interviews were conducted personally at the mother's home at 1 and 6 months postpartum and by telephone at 2 and 4 months. PARTICIPANTS: 287 mother-infant dyads. METHODS: Lactating mothers were randomly selected at two maternity wards (one public, one private) in Porto Alegre, Brazil. Data were analyzed using Kaplan-Meier survival curves and Cox multivariate regression. The outcome of interest was exclusive breastfeeding interruption before 6 months of the infant's life. FINDINGS: Nipple shields were used by 6.2 % of the women in the public maternity ward and by 25.8 % of those in the private setting. Median duration of exclusive breastfeeding was 11 days (95 %CI 0.0-36.9) among women who used the accessory vs. 89 days (95 %CI 60.8-117.2) among those who did not. Nipple shield use in the maternity ward was associated with exclusive breastfeeding interruption before 6 months of infant's life (adjusted risk ratio = 1.47; 95 %CI 1.01-2.15). The risk was higher in the first months of breastfeeding, ranging from 2.0 to 1.47 in the first and sixth months, respectively. CONCLUSIONS: The use of silicone nipple shields in the maternity ward increased the risk of exclusive breastfeeding interruption before 6 months of the infant's life, especially in the first months. These findings suggest caution in recommending this accessory to new mothers.