Context: The World Health Organization and the United Nations Children's Fund strongly discourage use of pacifiers because of their perceived interference with breastfeeding. Observational studies have reported a strong association between pacifier use and early weaning, but such studies are unable to determine whether the association is causal.
Objectives: To test whether regular pacifier use is causally related to weaning by 3 months postpartum and to examine differences in results according to randomized intervention allocation vs observational use or nonuse of pacifiers.
Design: Double-blind, randomized controlled trial conducted from January 1998 to August 1999.
Setting: Postpartum unit of a university teaching hospital in Montreal, Quebec.
Participants: A total of 281 healthy, breastfeeding women and their healthy, term singleton infants.
Interventions: Participants were randomly allocated to 1 of 2 counseling interventions provided by a research nurse trained in location counseling. The experimental intervention (n = 140) differed from the control (n = 141) by recommending avoidance of pacifier use and suggesting alternative ways to comfort a crying or fussing infant.
Main outcome measures: Early weaning, defined as weaning within the first 3 months, compared between groups; 24-hour infant behavior logs detailing frequency and duration of crying, fussing, and pacifier use at 4, 6, and 9 weeks.
Results: A total of 258 mother-infant pairs (91.8%) completed follow-up. The experimental intervention increased total avoidance of pacifier use (38.6% vs 16.0% in the control group), reduced daily use (40.8% vs 55.7%), and decreased the mean number of pacifier insertions per day (0.8 vs 2.4 at 4 weeks [P<.001]; 0.8 vs 3.0 at 6 weeks [P<.001]; and 1.3 vs 3.0 at 9 weeks [P =.004]). In the analysis based on randomized intervention allocation, the experimental intervention had no discernible effect on weaning at 3 months (18.9% vs 18.3% in the experimental vs control group; relative risk [RR], 1.0; 95% confidence interval [CI], 0.6-1.7), and no effect was observed on cry/fuss behavior (in the experimental vs control groups, respectively, total daily duration, 143 vs 151 minutes at 4 weeks [P =.49]; 128 vs 131 minutes at 6 weeks [P =.81]; and 110 vs 104 minutes at 9 weeks [P =.58]). When randomized allocation was ignored, however, we observed a strong observational association between exposure to daily pacifier use and weaning by 3 months (25.0% vs 12.9% of the exposed vs unexposed groups; RR, 1.9; 95% CI, 1.1-3.3).
Conclusions: We found a strong observational association between pacifier use and early weaning. No such association was observed, however, when our data were analyzed by randomized allocation, strongly suggesting that pacifier use is a marker of breastfeeding difficulties or reduced motivation to breastfeed, rather than a true cause of early weaning.