Pacifier Use and Early Life Weight Outcomes in the Intervention Nurses Start Infants Growing on Healthy Trajectories Study

Background: Although widely used by infants, little is known about the long-term effects of pacifiers. We investigated relationships between pacifier use in infancy and appetite, temperament, feeding, and weight outcomes through age 2 years using data from the Intervention Nurses Start Infants Growing on Healthy Trajectories study. Methods: Mother-newborn dyads were randomized to a responsive parenting intervention for obesity prevention or a control group. Infants with data on pacifier use (n = 250) were categorized as using a pacifier beyond early infancy (≥4 months of age) or not. Anthropometrics were measured at 6 months, 1, and 2 years with overweight defined as weight-for-length ≥95th percentile at 1 year and BMI ≥85th percentile at 2 years. Mothers completed questionnaires on temperament, appetite, and feeding. Results: Infants who used a pacifier at 4 months or later (68%) had greater conditional weight gain from birth to 6 months (p = 0.01), weight-for-length z-score at 1 year (p < 0.001), and BMI z-score at 2 years (p < 0.001) than infants who did not. Infants using a pacifier at ≥4 months were more likely to be overweight at ages 1 year (11.7% vs. 1.3%, p = 0.03) and 2 years (20.1% vs. 7.9%, p = 0.03). Pacifier use was associated with shorter breastfeeding duration and less responsive parent feeding styles, but these variables did not mediate the relationship between pacifiers and weight. Parent-reported temperament and appetite were unrelated to pacifier use. Conclusions: Pacifier use beyond early infancy is associated with accelerated infant growth and toddler overweight, although the reasons for this relationship are unclear.