There is limited published research regarding who and what influences a mother's decision to give her infant a pacifier. In view of the well documented, and confirmed in this study, negative association between pacifier use and breastfeeding duration, the results of this study are of importance to inform the design of any future interventions aimed at reducing pacifier use.
This study confirms the widespread use of pacifiers by Australian mothers reported in an earlier study  with eight out of 10 infants having been given a pacifier at some stage and seven out of 10 infants still using a pacifier at the time data for this study were collected. In the present study, women with a high school education were more likely to use a pacifier than women with a university education. This association between lower education level and pacifier use is supported by a previous study conducted in Brazil . Cultural differences in the use of pacifiers were observed in this current study with women born outside of Australian being significantly less likely to give their infant a pacifier than Australian born mothers. This finding is consistent with the findings of a multicentre study  which reported a widespread difference between countries in the prevalence of pacifier use ranging from 12.5% in Japan to 71% in the Ukraine. The findings of this study suggest that pacifier use in Australia, while approaching universality, is still significantly influenced by socioeconomic and cultural factors.
This study showed that almost 60% of mothers gave (or tried to give) their infant a pacifier to help settle them to sleep, which is consistent with the findings of a New Zealand study . Using pacifiers to soothe or comfort a crying or distressed infant, or to settle an infant to sleep, is likely to result in prolonged or extensive use of the pacifier as crying and sleep are both necessary and frequent behaviours in newborn infants. This may explain the early introduction of pacifiers by the majority of mothers (two thirds before 4 weeks) and the large percentage of mothers using pacifiers most days. The reportedly wide variation in the use of a pacifier between different countries  suggests that women from other cultures must use other methods that do not involve the use of a pacifier to effectively soothe their infant. Certainly, it has been shown that pacifiers are no more effective than the traditional ('attachment') methods of soothing (breastfeeding, carrying, rocking)  and the traditional methods of soothing may better support mother-infant bonding and subsequently breastfeeding success .
Another reason why relatively large numbers (20%) of mothers introduced a pacifier was 'because it is natural for babies to suck'. A similar reason was cited in a New Zealand study with almost half of the mothers reporting they used the pacifier to satisfy their infant's 'need' to suck . One of five mothers also gave their infant a pacifier to prevent them from sucking their thumb. However the use of a pacifier to discourage thumb sucking may replace one bad habit with another, both of which have been shown to increase the risk of dental malocclusion . A recent study reported that for each additional year of persistence with non-nutritive sucking, either pacifier use or finger sucking, there was a 2.3 times greater chance of dental malocclusion .
Finally, some mothers intentionally used the pacifier in order to stretch the time between breastfeeds (13%), to help remove the baby from the breast after a feed (6.8%) or to reduce 'non-nutritive' (or 'comfort') sucking on the breast (3.4%). It is important that breastfed infants are demand fed in the first weeks of life in order to establish the breast milk supply . The use of a pacifier for these reasons, particularly in the first four weeks of life, may disrupt the establishment of milk supply, thereby leading to a shorter duration of breastfeeding. The use of a pacifier to prolong the time between breastfeeds may reflect a mother's desire or naïve expectation of autonomy from their infant. This is consistent with the finding in numerous studies that women who choose to partially breastfeed do so in order that they can leave their child in the care of their partner or another person  or discontinue breastfeeding due to a sense of restriction .
The use of pacifiers may be related to a variety of inter-related factors. For instance, younger, less educated mothers may be less aware of alternative methods of soothing infants, whereas older, better educated mothers may use 'attachment methods' of soothing such as carrying, rocking, swaddling, singing and massage and only use 'non-attachment methods' of soothing (i.e. pacifiers) as a last resort. A Dutch multicultural study demonstrated that less educated women were less likely to carry, rock or swaddle their infant and more likely to give their infant a pacifier or night bottle compared with more educated women . It may be that the concomitant use of alternative non-attachment soothing methods such as a night bottle may be a confounder not considered in this or other studies. While plausible mechanisms for how a pacifier may contribute to the early cessation of breastfeeding have been postulated it is possible that the use of a pacifier may simply be a marker of breastfeeding problems that result in the early cessation of breastfeeding rather than an independent cause of breastfeeding cessation . For instance, prolonged suckling at the breast may be an indicator that an infant's nutritional needs are not being met, perhaps due to poor feeding technique, and warrants investigation by a health care professional.
Studies have shown that an infant's grandmothers (both maternal and paternal) are a key influence on the way a first-time mother cares for her child and they have been shown to be influential with regards to a woman's decision to initiate  and continue breastfeeding . They may be a source of both solicited and unsolicited advice, and in this study mothers and mothers-in-law were identified as a woman's primary source of advice regarding the use of a pacifier. Many of these grandmothers may not be aware of the negative association of pacifier use with breastfeeding duration and dental malocclusion, as much of this evidence has been published in the last 20 years or so. Interventions that aim to reduce the use of pacifiers should include opportunities for grandmothers to learn of the risks associated with early and frequent pacifier use. These may be in the form of print material specifically targeted at grandmothers and/or the opportunity to accompany their daughters/in-law to antenatal classes where feeding and pacifier use is discussed, to ensure that their knowledge aligns with current recommendations.
A third of mothers reported being advised to use a pacifier by a midwife or child health nurse. The questionnaire design did not allow for identification of whether women had received this advice from a hospital-based or community-based midwife or child health nurse. Based on the 'Ten steps to successful breastfeeding', Baby Friendly Health Initiative (BFHI) accredited hospitals discourage the use of artificial teats or pacifiers in breastfeeding mothers . Future research should distinguish between hospital-based and community-based workers in order to investigate further the association between the advice and BFHI accreditation. Nevertheless, ensuring the currency and quality of midwife and child health nurse advice is important.
This study confirmed the findings of numerous other studies that there is a negative association between pacifier use and breastfeeding duration, and more specifically, that the association is related to the time of introduction and frequency of use. Our results indicate that infants given a pacifier prior to four weeks of age and those using pacifiers most days had a three-fold risk of shorter breastfeeding duration, independent of maternal education and age. These results are similar to those of two Australian studies, supporting a stronger association between shorter breastfeeding duration and early pacifier introduction compared with later introduction [7, 17]. Previous research has also found similar results with regards to frequency of use [8, 10].
This study has a number of limitations, firstly the restriction of this study to first time mothers means that results cannot be generalised to all mothers, although previous research indicates that the association between pacifier use and breastfeeding duration exists in both primiparous and multiparous mothers . A major limitation of the study is that the sample is not representative of the population from which it was drawn, further limiting the generalizability of results. While 76% of women contacted shortly after delivery agreed to be contacted when their infants were older, only 44% consented to participate further when approached the second time. The relatively low response rate is consistent with other Australian studies that involve an active intervention [28, 29]. First time mothers were probably less inclined, once they had realised how time consuming caring for a young infant can be, to participate in a study which possibly would require them to attend education sessions. However this also means that the significance of some results to the general population may have been underestimated. For example, participants were older and better educated and likely therefore to be more health conscious. Given that an education level lower than university was positively associated with both early introduction and more frequent use of pacifiers, this may lead to an underestimation of both these measures of pacifier use. The investigation of pacifier use was not the primary purpose of the NOURISH study, which limited the ability to investigate pacifier use more extensively, particularly because the design of the study was retrospective, introducing potential recall bias, and preventing investigation of the causality of the relationship between pacifier use and breastfeeding duration.
Nevertheless, this study has several strengths and confirms the findings of earlier studies. As previously identified breastfeeding rates and rates of pacifier use vary greatly between countries , highlighting the need for country specific data, which this study provides being one of only a handful of studies conducted in Australia. The sample size of this study was relatively large, and inclusion of data from two cities increases its generalizability. The scope of this study is greater than previous Australian studies, being the first to investigate both who advises first-time mothers to give a pacifier, and the reasons for which they first give a pacifier to their infant.