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Cochrane Database of Systematic Reviews Protocol - Intervention

Pacifier use versus no pacifier use in breastfeeding term infants for increasing duration of breastfeeding

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Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To assess the effect of pacifier use versus no pacifier use in healthy full‐term newborns whose mothers have initiated breastfeeding and intend to exclusively breastfeed, on the duration of breastfeeding, other breastfeeding outcomes and infant health.

Background

The superiority of breast milk in providing balanced nutrition, protection against allergy and infection in newborns is well documented (Chandra 1979; Oddy 2001). Thus, the World Health Organization (WHO) Expert Consultation recommends that infants be exclusively breastfed (infant receives only breast milk with no other liquids including water or solids) up to the first six months of life and as a dietary supplement thereafter. In order to successfully initiate and maintain breastfeeding for longer duration, and avoid supplementary feeding, the WHO's Ten Steps to Successful Breastfeeding recommends total avoidance of artificial teats or pacifiers for breastfeeding infants. The use of a pacifier, a non‐nutritive sucking device to calm an infant, is relatively widespread and has become a cultural norm in many parts of the world (Barros 1995). Pacifiers are often believed to be harmless or even necessary and beneficial for infants' development (Victora 1997). However, the use of pacifiers for breastfeeding infants remain controversial.

Breastmilk production and supply are maintained by frequent suckling of the breast and nipple stimulation (Aarts 1999; Neville 1988). In order to breastfeed successfully, infants must learn to attach and suckle properly at the breast during the first few days of life. Effective breast sucking technique requires the infant to have a wide open mouth, with the tongue under the areola. Expression of milk from the breast is by slow and deep sucks, while sucking on a pacifier is basically superficial sucking (Righard 1992) where the infant is sucking on a teat with short and fast sucks using minimal effort. The mechanical differences between sucking at the breast and sucking on a pacifier may result in 'nipple confusion' (Gomes 2006; Neifert 1995), incorrect latching onto the breasts and superficial sucking on the mother's nipples (Righard 1998). Improper technique of sucking on the breasts may lead to cracked nipples and mastitis, which may further impede breastfeeding. Evidence from a cohort study reported that breastfeeding difficulties during the first week postpartum were significantly associated with termination of breastfeeding by week 10 of life (Scott 2005). There are beliefs, based on observational evidence, that early exposure of infants to the pacifier is associated with cessation of exclusive breastfeeding by 3 to 6 months (Mascarenhas 2006; Scott 2005), and overall breastfeeding by 12 months (Scott 2005). Offering the pacifier instead of the breast to calm the infant may lead to less frequent episodes of breastfeeding. This in turn may reduce breast milk production and shorten duration of breastfeeding in the long term (Howard 1999). Furthermore, infants may get used to the pacifier, and develop a preference for an artificial teat instead of the mother's nipple.

On the other hand, it remains unclear whether breastfeeding cessation and a maternal intention to wean the infant from exclusive breastfeeding precedes the use of a pacifier or vice versa. It is possible that a mother may have experienced breastfeeding difficulties early and intended to stop breastfeeding, by introducing the pacifier to the infant in preparation to take on bottlefeeding. Interestingly, evidence also shows that pacifiers can have a positive effect on breastfeeding, as they may help to take the infant off the breast and thereby increase the interval between feedings and possibly breast milk intake by the infant (Victora 1997). Observational evidence also indicates that occasional use of the pacifier has no effect on breastfeeding duration compared to daily pacifier use (Ullah 2003; Vogel 2001) and thus it remains unclear whether pacifiers are an independent causal factor for reducing breastfeeding duration. In addition, the use of pacifiers might be protective against sudden infant death syndrome (Mitchell 2006; Saririan 2006), although its mechanism is unknown. However, prolonged non‐nutritive sucking on the pacifier is associated with an increased risk of recurrent acute otitis media (Jackson 1999), oral candidiasis (Darwazeh 1995) and dental malocclusion (Caglar 2005).

Therefore, the aim of this review is to study the effect of pacifier exposure versus no pacifier exposure in healthy infants whose mothers have initiated breastfeeding and intend to exclusively breastfeed, on the duration of breastfeeding and infant health.

Objectives

To assess the effect of pacifier use versus no pacifier use in healthy full‐term newborns whose mothers have initiated breastfeeding and intend to exclusively breastfeed, on the duration of breastfeeding, other breastfeeding outcomes and infant health.

Methods

Criteria for considering studies for this review

Types of studies

All randomised controlled trials including quasi‐randomised trials.

Types of participants

Healthy full‐term newborns who have initiated breastfeeding regardless of whether they were born at home or in the hospital. We will exclude studies which include newborns who were exposed to bottlefeeding prior to enrolment from the study.

Types of interventions

A group in which pacifier use is either encouraged or not restricted versus a group with advice against pacifier use after initiation of breastfeeding. We will exclude studies which evaluate occasional pacifier use in the clinical setting to provide analgesia for procedural pain.

Types of outcome measures

Definition

Labbok 1990 defines full breastfeeding as a situation where infants receive breast milk either exclusively (ie, no other solid or liquid, including water, is offered) or almost exclusively (ie, supplemental liquids, other than milk formula, are offered infrequently). Partial breastfeeding is defined as a situation where the infant is breastfed and also receives other milk supplements regularly.

Primary outcome

The primary outcome is duration of breastfeeding as measured by one of the following:

  1. mean duration of full breastfeeding (months) as defined by Labbok 1990;

  2. mean duration of any breastfeeding (months);

  3. proportion of infants being fully or partially breastfed at 3, 4 and 6 months of age.

Secondary outcome

  1. Rate of breastfeeding difficulties (cracked nipples, breast engorgement, mastitis).

  2. Maternal satisfaction and level of confidence in parenting.

  3. Mean frequency of infant crying and fussing per day.

  4. Infants' health: incidence of sudden infant death syndrome, oral candidiasis, otitis media and dental malocclusion.

Search methods for identification of studies

Electronic searches

We will contact the Trials Search Co‐ordinator to search the Cochrane Pregnancy and Childbirth Group’s Trials Register. 

The Cochrane Pregnancy and Childbirth Group’s Trials Register is maintained by the Trials Search Co‐ordinator and contains trials identified from:

  1. quarterly searches of the Cochrane Central Register of Controlled Trials (CENTRAL);

  2. weekly searches of MEDLINE;

  3. handsearches of 30 journals and the proceedings of major conferences;

  4. weekly current awareness alerts for a further 44 journals plus monthly BioMed Central email alerts.

Details of the search strategies for CENTRAL and MEDLINE, the list of handsearched journals and conference proceedings, and the list of journals reviewed via the current awareness service can be found in the ‘Specialized Register’ section within the editorial information about the Cochrane Pregnancy and Childbirth Group.

Trials identified through the searching activities described above are each assigned to a review topic (or topics). The Trials Search Co‐ordinator searches the register for each review using the topic list rather than keywords. 

We will not apply any language restrictions.

Data collection and analysis

Selection of studies

We will use the standard methods of The Cochrane Collaboration in the consideration of trials for inclusion. We will work independently to identify trials for inclusion. The three authors will independently evaluate methodological quality and extract the trial data as described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2006). We will resolve differences in interpretation by discussion.

Data extraction and management

We will design a form to extract data. At least two review authors will extract the data using the agreed form. We will resolve discrepancies through discussion. We will use the Review Manager software (RevMan 2003) to double enter all the data or a subsample.

When information regarding any of the above is unclear, we will attempt to contact authors of the original reports to provide further details.

Assessment of methodological quality of included studies

We will assess the validity of each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2006). Methods used for generation of the randomisation sequence will be described for each trial.

(1) Selection bias (randomisation and allocation concealment)

We will conduct quality assessment for each trial, using the following criteria:
(A) adequate concealment of allocation: such as telephone randomisation, consecutively numbered, sealed opaque envelopes;
(B) unclear whether adequate concealment of allocation: such as list or table used, sealed envelopes, or study does not report any concealment approach;
(C) inadequate concealment of allocation: such as open list of random‐number tables, use of case record numbers, dates of birth or days of the week.

(2) Attrition bias (loss of participants, for example, withdrawals, dropouts, protocol deviations)

We will assess completeness to follow up using the following criteria:
(A) less than 5% loss of participants;
(B) 5% to 9.9% loss of participants;
(C) 10% to 19.9% loss of participants;
(D) more than 20% loss of participants.

We will not include studies for analysis if:

(A) more than 20% of participants excluded;

(B) more than 20% of analysis not in randomisation groups and not possible to restore participants to correct group.

(3) Performance bias (blinding of participants, researchers and outcome assessment)

We will assess blinding using the following criteria:

  1. blinding of participants (yes/no/unclear);

  2. blinding of caregiver (yes/no/unclear);

  3. blinding of outcome assessment (yes/no/unclear).

Measures of treatment effect

We will carry out statistical analysis using the Review Manager software (RevMan 2003). We will use fixed‐effect meta‐analysis for combining data in the absence of significant heterogeneity if trials are sufficiently similar. If heterogeneity is found, we will explore this using sensitivity analysis followed by random‐effects if required.

Dichotomous data

For dichotomous data, we will present results as summary relative risk with 95% confidence intervals.

Continuous data

For continuous data, we will use the weighted mean difference if outcomes are measured in the same way between trials. We will use the standardised mean difference to combine trials that measure the same outcome, but use different methods. If there is evidence of skewness, this will be reported.

Dealing with missing data

We will analyse data on all participants with available data in the group to which they are allocated, regardless of whether or not they received the allocated intervention. If in the original reports participants are not analysed in the group to which they were randomised, and there is sufficient information in the trial report, we will attempt to restore them to the correct group.

Assessment of heterogeneity

We will apply tests of heterogeneity between trials, if appropriate, using the I‐squared statistic. If we identify high levels of heterogeneity among the trials (exceeding 50%), we will explore it by prespecified subgroup analysis and perform sensitivity analysis. A random‐effects meta‐analysis will be used as an overall summary if this is considered appropriate.

Subgroup analyses

We will conduct planned subgroup analyses classifying whole trials by interaction tests as described by Deeks 2001.

We plan to carry out the following subgroup analyses: by the infant age when the pacifier was introduced (0 to 8 weeks, 8 to 16 weeks, after 16 weeks), on the duration of breastfeeding as measured by the following:

  1. mean duration of exclusive breastfeeding (months);

  2. mean duration of any breastfeeding (months);

  3. proportion of infants exclusively or partially breastfed at 4 and 6 months of age.

Sensitivity analyses

We will carry out sensitivity analysis to explore the effect of trial quality. This will involve analysis based on an A, B, C, or D rating of selection bias and attrition bias. Studies of poor quality will be excluded in the analysis (those rating B, C, or D) in order to assess for any substantive difference to the overall result.