## 4 Discussion  
Our results highlight that pacifier use improves SpO2 levels in infants during wake time. They also show that the supine position at 30\({}^{\circ}\) inclination does not improve SpO2 levels during wake time. PacificiF use, thus, seems to have a positive effect on peripheral capillary oxygen saturation. No problems or irritation of the oral mucosa related to the pacifier use were observed by the parents or medical staff during the tests. The results are line with the literature, although there are few articles on this subject. Analyzing arterial oxygen saturation, [PERSON] (2002) demonstrated that pacifier use during sleep improved the maintenance of patent airways and an adequate oral airflow in healthy infants born at term, especially for patients suffering from nasal occlusion [17]. This result was correlated with the fact that a pacifier pushes the tongue forwards and upwards, favoring the airflow around the pacifier, and between the tongue and the palate. [PERSON] (2007) hypothesized that the association between pacifier use and a reduced risk of SIDS could be related to the forward movement of the maxilla and, consequently, of the tongue, which helps to maintain patent upper airways. [16]  
We thus measured the distance between the ear and the most prominent point of the chin in pre-term infants before and after using a pacifier for around 15 min. A small but significant advancement of the maxilla was observed, which was maintained after the pacifier had been removed. This confirmed the positive effect of the pacifier on the upper airways. Data from lateral neck radiographs also suggest an association between ALTE and narrowing of the upper airways [25]). [PERSON] and [PERSON] conducted a study at the Pediatric Unit of the Hospital Filippo del Ponte (Varese, Italy) between 2017 and 2018. They found that pacifier use in infants aged between 0 and 2 years, who were hospitalized after an ALTE/BRUE episode, significantly reduced the incidence of apnea and hypopnea (AHI), that is, the absolute number of apneas/hypopneas per hour, measured using a complete polysomnography during afternoon rest [18]. With regard to the position, our results showed no improvement in SpO2 levels in the supine position at 30\({}^{\circ}\)/in sitting position compared to the those measured in the supine position at 0\({}^{\circ}\). This study confirms that the use of pacifiers led to an improvement in the average SpO2 in both positions tested. The results also suggest that the improved SpO2 levels are directly correlated to pacifier use and are not impacted by the different positions tested. Figure 1: Main results. Pacifiers thus represent an excellent tool not only in preventing SIDS, in calming the baby, in reducing the perception of pain during painful procedures, and in reducing finger sucking habits, but also in improving breathing both during sleep and while awake. Pacifiers should thus be used after the first month of life, once breastfeeding has been consolidated, and no later than 36 months of age to prevent misalignment of the dental arch. Recommendations for the Correct Use of the PacificThe use of pacifiers has always been a topic of interest for both parents and the scientific world. To date, with a few exceptions, all aspects of the correct use of the pacifier have been fully clarified. Simple and practical clinical recommendations can thus be given [26]. Some key recommendations are as follows: the use of a pacifier reassures the infant and the family. However, pacifiers should not be used as a substitute for the parent-child relationship and parents should only resort to it when the newborn would clearly benefit from it, and not when the infant's desire to communicate is evident. In fact, a pacifier should not be used to stop a newborn from crying, which in most cases is an expression of a need that should not be ignored [7; 27; 28]. To prevent malocclusion, it is advisable to use a pacifier for 24 months and stop before 36 months.