Early tactile parent–infant interactions are very important and play a central role in an infant’s physical, social and emotional development [1]. During early parent–infant interactions, countless exchanges involve tactile contact behaviors, which are expressed through skin-to-skin contact (i.e., a parent holding his/her infant and providing affectionate touch, such as caresses, hugs, and kisses) and are not necessarily related to a particular aim. A plethora of studies have documented that mothers’ early tactile contact behaviors have positive effects both on full-term ^[2][3][2,3] and preterm infants ^[4][5][4,5], while research on paternal tactile behaviors is still scant and its association with infant outcomes remains poorly investigated, especially in full-term infants. This is likely due to the fact that mothers historically spent more time in caregiving compared to fathers [6], although this has now changed, especially in Western societies [7], and nowadays fathers spend much more time caring for, and interacting with, their children than in the past [8]. Findings from industrialized countries reveal that there has been a three- to six-fold increase in father engagement in caregiving activities in the last fifty years ^[9][10][9,10]. Fathers spend much more time not only in caregiving routines (e.g., diaper changing, feeding, playing, …) ^[11][12][11,12], but also in a countless number of embodied interactions [13]. A variety of fathers’ behaviors and their effect on infants’ development have been observed, for example, attachment [14], speech [15], play [16], sensitivity [17], and fathers’ representation of their children [18], and tools have been developed to assess the quality of father–infant interaction [19]. Nevertheless, paternal touch behaviors have remained largely unexplored.

Most studies on fathers’ touch were conducted with preterm infants and their fathers, with a particular focus on skin-to-skin care (SSC). SSC is a practice where a naked infant is placed on his/her parent’s bare chest. It is commonly used immediately after birth with full-terms, or any time an infant needs to be comforted or calmed down. If necessary, infants can wear a diaper and/or a cap and parents and infants can be covered with a blanket or linen. Importantly, given that it is a very low-cost practice that does not require specific materials and equipment, it is suitable for all cultural backgrounds [20]. Research has shown several effects of SSC on preterm infants and their fathers, such as stress reduction [21], changes in paternal oxytocin levels [22] and effectiveness in neonatal pain control [23]. Previous reviews demonstrated that SSC with fathers has a beneficial impact on infants (both pre- and full-terms) and fathers’ outcomes ^[24][25][24,25]. Nevertheless, these studies did not consider any other paternal touch behaviors such as spontaneous touch (i.e., all behaviors used by parents to touch infants for different reasons such as playing, cleaning, getting attention, affection expression), and only a limited number of studies, e.g., ^[26][27][28][26,27,28], have investigated spontaneous touch (ST).

One study reports fathers’ oxytocin, cortisol, and testosterone responses to their first holding of their infants, comparing standard routine holding with SSC holding ^[29][41]. Oxytocin was higher after first holding in both groups and there was no difference in oxytocin levels following routine holding vs. SSC holding. Furthermore, fathers whose testosterone increased and oxytocin decreased during first holding showed greater involvement, more direct father–infant caregiving and greater father–infant bonding compared to fathers whose testosterone and oxytocin declined ^[29][41].

Two studies analyzed vocalization behavior during SCC contact. Velandia and colleagues ^[30][32] found that fathers directed more soliciting sounds and speech to their infants during SCC compared with routine care. In another study, Velandia and collaborators ^[31][34] documented that fathers appeared to address less speech to girls vs. boys during SSC.

Most research focused on psychological variables, meaning fathers’ experienced attachment to their infants. In only one study, psychological variables were anxiety and depression ^[32][38]. Moreover, most studies compared father–infant dyads during SSC to father–infant dyads during standard care (i.e., simply holding their infants without skin-to-skin contact). Chen and colleagues ^[33][35] recruited 92 fathers and their full-term newborns and divided the sample into two groups: fathers during SSC and fathers during standard care. Fathers filled out the Father–Child Attachment Scale ^[34][43], a questionnaire measuring attachment on a number of subscales (exploring, touching, caring, and talking) before and after SSC and standard care (i.e., three days after SSC or standard care). Subscale scores post-SCC/standard care were significantly higher in the SSC group than in the standard care group. The difference in total score pre- vs post-SCC/standard care was higher for the SSC group than in the standard care group.

Similarly, one study recruited full-term healthy infants born by caesarean section and fathers were divided into two groups: SSC vs. routine care ^[32][38]. Fathers filled out self-report questionnaires about anxiety, depression, and role attainment. Fathers who engaged in SSC had lower anxiety/depression and higher paternal role attainment scores after SSC. Yilmaz and colleagues ^[35][42] showed that similar findings are true also in a middle-term perspective. They compared father–infant attachment—as measured by the Paternal–Infant Attachment Scale ^[36][44]—in fathers during SSC immediately after birth and fathers who did not engage in SSC 6-to-12 months after birth. Attachment was more intense in fathers who engaged in SSC, especially in first-time fathers.

In Huang et al.’s study ^[32][38], some children were exposed to SSC, others received routine care in an incubator next to their father. Infants who received SSC had more stable heart rates and a significantly higher forehead temperature. Similarly, full-term newborns born by elective caesarean section who experienced SSC exhibited higher and more stable heart rates compared with infants who received routine care (i.e., placed in a crib) or babies placed in their fathers’ arms ^[37][40].

Huang et al. ^[32][38] also collected data about crying and when children were breastfed and for how long. Infants in the SSC group cried for a shorter time period and showed breastfeeding behaviors earlier than infants in the routine care group. Ayala et al. ^[37][40] compared infants placed in a cot and in their fathers’ arms with infants who were exposed to SSC. The latter exhibited higher wakefulness (i.e., the condition of being alert, rather than sleepy) as assessed by the Neonatal Behavioral Assessment Scale (NBAS, ^[38][45]).

Spontaneous touch in the included studies was observed only with reference to fathers’ and infants’ biophysiological markers (e.g., heart rate, respiratory rate, and hormonal levels).

One study measured paternal oxytocin and coded fathers’ touch during a free play interaction with their 6-month-old infants [26]. They found that physical touch, particularly playful proprioceptive touch, is associated with higher oxytocin levels in fathers. Tactile behaviors, such as cradling, affectionate touch, proprioceptive touch, and stimulatory touch, were coded during interaction between fathers and their 4–6-month-old infants ^[39][31]. Only fathers exhibiting high levels of stimulatory contact showed an oxytocin increase.

One study examined the effects of oxytocin administration on paternal behavior and its effects on interactions between fathers and their 5-month-old infants [28]. Participants were divided into two groups: one received intranasally administered oxytocin, while the other received a placebo. Participants were blind to the group they belonged to. Fathers who received oxytocin exhibited more infant-directed touch, positive vocalizations, and encouragement of infants’ social initiative compared to fathers receiving the placebo. Gordon and colleagues ^[40][36] explored the interaction between testosterone and oxytocin during transition to parenthood immediately after birth in fathers (and mothers). At 1- and 6-months postpartum, they assessed plasma testosterone and oxytocin concentrations, and they microcoded father–infant interactions of affectionate touch and parent–infant synchrony (i.e., parent engagement in social gaze, affectionate touch, and “baby-talk” vocalizations while the infant looked at the parent and expressed positive affect). Results highlighted that, only when testosterone was high, did negative associations emerge between oxytocin and father affectionate touch.

Cardiac activity (i.e., ECG) and breathing movements before, during, and after a stroking period were collected in 4–16-week-old full-term infants ^[41][39]. Findings suggested that paternal gentle stroking induced an increase in respiratory sinus arrhythmia (RSA, an index of cardiac vagal activity) in infants.

In several studies, Feldman and colleagues ^[39][40][42][31,33,36] examined the association between endocrine and hormonal biomarkers (oxytocin and testosterone concentrations) and mothers and fathers’ touch behaviors in association with playful interactions with their infants during the postpartum period. Regardless of mother/father and type of touch (e.g., affectionate, functional, stimulatory, and accidental touch), parents with high plasma oxytocin touched their infants more than parents with low oxytocin ^[42][33]. Notwithstanding this, significant differences emerged in another study that assessed oxytocin levels in mothers and fathers after they had been engaged in a 15-min play-and-contact interaction with their 4–6-month-old infants ^[39][31]. Although baseline oxytocin (plasma and salivary) levels in mothers and fathers were similar, oxytocin was associated with a parent-specific mode of tactile contact. An oxytocin increase after mother–child interaction was observed only in mothers who provided high levels of affectionate contact (e.g., kisses, caresses, and light pokes). Only fathers exhibiting high levels of stimulatory contact (e.g., changing infants’ position in space) showed an oxytocin increase.

Along with oxytocin, testosterone has important implications for the development of social attachment ^[43][46]. One study examined potential interactions between these hormones and the development of mothering and fathering in the months postpartum ^[40][36]. Specifically, the authors investigated how circulating levels of oxytocin and testosterone were related to affectionate touch and parent–infant synchrony during 5-min play interactions in 1–6-month-old infants. A positive association was found between oxytocin and affectionate touch among mothers with high testosterone levels; in contrast, high testosterone levels in fathers provided the background for negative associations between oxytocin and paternal touch ^[40][36].

One study compared the impact of paternal and maternal affectionate touch on infants’ physiological regulation in terms of RSA, which reflects the specific component related to the parasympathetic inhibitory influence on the heart mediated by the vagus nerve ^[41][39]. Parental touch behavior was observed during a 3-min affectionate touch period and compared with the baseline and poststroking periods in a group of mothers and fathers and their 4–16week-old infants. Results showed that both mothers’ and fathers’ stroking speed occurred within the optimal stimulation range of C-tactile (CT) afferents, a specific class of cutaneous unmyelinated, low-threshold, mechano-sensitive nerves hypothesized to be involved in bonding ^[44][47]. Importantly, no significant difference between the impact of paternal and maternal affective touch on RSA was found. This suggests that parental affective touch has a beneficial impact on parasympathetic infant regulation, regardless of whether it comes from mothers or fathers.

Another study examined the potential differences in negative emotionality between infants who experienced maternal SSC and those who experienced paternal SSC ^[30][32]. Although paternal SSC was associated with less crying, infants whined more with fathers than mothers. No significant differences emerged in the quiet state time. A similar procedure analyzed breastfeeding and crying behaviors in newborns, highlighting that fathers touched their infants significantly less than mothers during SSC and breastfeeding started later when SSC was provided by fathers ^[31][34]. Another study enrolled full-term infants born by elective caesarean section ^[45][37]. Infants were divided into three groups, depending on what happened immediately after surgery: maternal SSC, paternal SSC, and no SSC. Participants were asked to answer an ad hoc interview about infants’ breastfeeding habits immediately after birth and 3 and 6 months later. Immediately after birth, infants who received maternal SSC were more likely to receive exclusive breastfeeding (i.e., the infant receives only breast milk; no other liquids or solids are given—not even water—with the exception of oral rehydration solution, or drops/syrups of vitamins, minerals or medicines) than infants who received paternal SSC or routine care. These results were replicated at three and six months, even if the percentage of infants receiving exclusive breastfeeding dropped.