All day-long pacifier use and intelligence quotient in childhood: A birth cohort study

Paediatr Perinat Epidemiol. 2021 Jul;35(4):511-518. doi: 10.1111/ppe.12752. Epub 2021 Feb 11.

Abstract

Background: Literature on pacifier use remains controversial, but mostly suggests an inverse association with childhood intelligence.

Objectives: The objective of this study was to assess the association between pacifier use and intelligence quotient (IQ) in six-year-old children from a birth cohort.

Methods: Data from 3532 children from the 2004 Pelotas (Brazil) Birth Cohort were analysed. Children were recruited and assessed at birth and followed up at 3 months, and 1, 2, 4, and 6 years. Data on pacifier use duration and intensity were obtained via interviews with mothers in all six follow-up visits. IQ was estimated at 6 years using the Wechsler Intelligence Scale for Children and standardised for the analyses. Crude and adjusted coefficients were calculated (linear regression) for all the data collected in follow-up assessments for pacifier use.

Results: IQ was inversely associated with all pacifier use indicators. Children who used a pacifier all day long (ADL) at any follow-up showed an IQ 0.18 (95% confidence interval [CI] 0.11, 0.24) standard deviations below those who never used it ADL, after adjusting for confounders. The strength of association increased with number of assessments reporting ADL pacifier use, from a reduction in IQ of 0.13 (95% CI 0.06, 0.21) to 0.34 (95% CI 0.15, 0.52) standard deviations for ADL use in one and in all four follow-up visits, respectively.

Conclusions: We found a strong association between intense pacifier use up to 4 years of age and lower IQ at 6 years. A dose-response gradient was observed, with greater IQ deficits in children who used a ADL pacifier for longer durations. The mechanisms underlying this association need to be clarified. One hypothesis is that children using a pacifier, especially those who use it more intensely, are less stimulated.

Keywords: birth cohorts; children; habits; intelligence tests; pacifier.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Child
  • Child Development*
  • Cohort Studies
  • Female
  • Humans
  • Infant, Newborn
  • Intelligence
  • Intelligence Tests
  • Pacifiers* / adverse effects