1. Objectives

To evaluate the effect of restricted pacifier use compared with unrestricted pacifier use in healthy term newborns on breastfeeding duration, other breastfeeding outcomes, and infant health

2. How studies were identified

The following databases were searched in June 2016:

• Cochrane Pregnancy and Childbirth Group’s Trials Register
• CENTRAL (The Cochrane Library 2016)
• MEDLINE
• EMBASE
• CINAHL

Relevant journals, conference abstracts, and reference lists were also searched

3. Criteria for including studies in the review

3.1 Study type

Randomized controlled trials, including quasi-randomized and cluster-randomized trials

3.2 Study participants

Healthy term newborns whose mothers had initiated breastfeeding and intended to exclusively breastfeed

(Studies enrolling newborns exposed to bottle-feeding were excluded)

3.3 Interventions

Advice to restrict pacifier use compared with unrestricted or actively encouraged pacifier use in breastfeeding infants from the postpartum period until six months of age

3.4 Primary outcomes

• Prevalence or proportion of infants being fully or partially breastfed at three, four, and six months of age
• Duration of exclusive breastfeeding
• Duration of any breastfeeding

Secondary outcomes included breastfeeding difficulties (cracked nipples, mastitis, breast engorgement), maternal satisfaction and level of confidence in breastfeeding, episodes/frequency of infant crying or fussing, incidence of sudden infant death syndrome, infant oral candidiasis, infant otitis media, and infant dermal malocclusion

4. Main results

4.1 Included studies

Three randomized controlled trials, enrolling 1915 infants, were included in this review

• Two of the three trials, involving a total of 1302 infants, contributed data to analyses
• In the trial that did not contribute data, 602 mothers who intended to breastfeed their healthy term infants were randomized to either the experimental group where breastfeeding was encouraged and pacifiers were forbidden, or to the control group where pacifiers were offered without restriction
• In one multicentre trial of 281 women and their healthy term infants, women were recruited before breastfeeding was established, and all women were motivated to breastfed. The experimental group was randomized to receive counselling to avoid pacifier use when the infant cried or fussed and to instead offer the breast or try to carry or rock the infant. The control group was counselled on all options for calming the infant, including breastfeeding, carrying, rocking, and pacifier use
• One multicentre trial enrolled 1021 mothers who were already successfully breastfeeding at two weeks and intended to continue for at least three months. Women were randomized to receive advice to offer pacifiers or to not offer pacifiers as part of the counselling given on comforting crying infants

4.2 Study settings

• Argentina, Canada, and Switzerland (data not included in analyses)
• Women were recruited via hospitals in the postpartum period: two studies recruited mothers during the immediate postpartum period while they stayed in hospital, and one study recruited women at two weeks postpartum

4.3 Study settings

How the data were analysed
Restricted or no pacifier use was compared with unrestricted pacifier use. Dichotomous outcomes were pooled in fixed effect meta-analysis to generate risk ratios (RR) with corresponding 95% confidence intervals (CI). If substantial heterogeneity (I²>30%) had been detected and an overall summary was still deemed meaningful, random effects meta-analysis was to be used. Due to a lack of data, sensitivity analyses by trial quality were planned but not conducted. The following subgroup analyses were planned to investigate potential sources of heterogeneity:

• Primiparous versus multiparous mothers
• Vaginal delivery versus caesarean section

Results
Restricted or no pacifier use versus unrestricted pacifier use
Primary outcomes
No difference between restricted and unrestricted pacifier use groups was found in the proportion of infants who were exclusively breastfed at three months of age (RR 1.01, 95% CI [0.96 to 1.07], 2 trials/1228 infants; I²=0.00%) or at four months of age (RR 1.01, 95% CI [0.94 to 1.09], 1 trial/970 infants). The proportion of infants receiving any breastfeeding at three (RR 1.00, 95% CI [0.98 to 1.02], 2 trials/1228 infants; I²=0.00%) or four months (RR 0.99, 95% CI [0.97 to 1.02], 1 trial/970 infants) also did not differ between treatment and control groups.

Additional outcomes
No data was available for analysis. In the study including 281 infants, it was reported that restriction of pacifiers had no effect on cry or fuss behaviour at four, six, or nine months of age and also had no effect on the risk of weaning before three months of age.

5. Additional author observations*

Using GRADE criteria, the quality of the evidence for the outcome proportion of infants exclusively breastfed at four to six months of age was rated as moderate, with downgrading due to imprecision as data were obtained from only one trial. All three trials were at low risk of allocation concealment bias, and in the two trials contributing data to analyses, the research nurse and outcome assessors were blinded. The mothers enrolled in all included trials were highly motivated to continue breastfeeding, and thus the findings may not be generalizable to all women.

The evidence included in this review suggests that pacifier use by women highly motivated to begin or to continue breastfeeding does not affect the duration of breastfeeding up to four months postpartum.

Further research among women less motivated to breastfeed is required. In addition, the potential adverse effects of pacifier use on infant and maternal health should be investigated in randomized controlled trials.