Inclusion criteria

Infants are eligible to be included in the study if they meet the criterion of: (1) birth before 34 weeks PMA. The reason for choosing a cut-off of 34 weeks (instead, for instance, 32 weeks, ie, the cut-off for very preterm birth) is to increase the number of participant families, given the difficulties of recruitment in the NICU. Furthermore, this criterion is in line with other studies on maternal caregiving behaviour during the stay in the NICU,50 and on mother–preterm infant interaction after discharge.57 ,65

Mothers and fathers are eligible to be included in the study if they meet the following criteria: (1) both were born and grew up in Italy; (2) both have given their consent to participate in the study.

Exclusion criteria

Infants will be excluded from the study if: (1) they have perinatal asphyxia; (2) they have neurologic pathologies (periventricular leucomalacia up to stage I and/or intraventricular haemorrhage up to stage II); (3) they experience malformation syndromes and/or major malformations; (4) they have sensory deficits (detected by regular medical checks performed during hospitalisation); (5) they present metabolic or genetic disease.

Mothers and fathers will be excluded from the study if: (1) they are not of Italian origin; (2) they have a psychiatric illness; (3) they have issues with drug or substance abuse; (4) they are not living together; (5) they are adopting parents; (6) they are a same-sex couple.

To participate in the study it is necessary that both parents and infants meet the inclusion and exclusion criteria.

Ethnographic observation in NICU

Ethnography is a methodological approach which involves the researcher participating overtly in the lives of people, in this case in the NICU.66 ,67 Ethnographers work by ‘watching what happens, listening to what is said and/or asking questions through informal and formal interviews and collecting documents’.68 Ethnographic observation was selected over other methods to inform this study and to prepare the best conditions for accomplishing this study, as it aims (1) to minimise the risks potentially associated with having an observing researcher within the observed social context (eg, perception of intrusiveness, minor spontaneity during videotaped interactions and/or interviews) and (2) to obtain rich qualitative data from participant observation in social interactions which take place in that context. This is even more important in a stressful context such as the NICU, where social interactions are particularly vulnerable.

Initially, the researcher (the psychologist–psychotherapist and PhD student who is the first author) goes through a familiarisation period with the parents in the NICU. During this period and later on too, the researcher observes the interactions between (1) parents and their preterm infants, (2) mothers and fathers, (3) parents and staff (nurses, neonatologist and psychologist) and (4) infant and nurses; he attends meetings between neonatologists, observes conversations between staff and parents and he also holds informal talks with mothers and fathers. Then the researcher presents the research project to the parents who meet the inclusion criteria and ‘follows’ the recruited families until the infant's discharge from the NICU. We think that qualitative data obtained from ethnographic observation can offer a main contribution to the understanding of the NICU-related stress and the impact of preterm birth and ensuing hospitalisation on mothers' and fathers' emotional experiences, their relationship and how they cope with the stay in the NICU: all factors that might affect parent–infant relationship and the quality of mother–infant and father–infant interactions. Finally, ethnographic observation is used to identify the best conditions—infant's behavioural states, time, position and so on—for video recording parent–infant face-to-face interaction (with the preterm infant in a heated cot) in the NICU.

Recruitment

All parents (mothers and fathers) of preterm infants born between 17 September 2015 and 31 March 2017 and hospitalised at level III NICU of the Borgo Roma Hospital—Azienda Ospedaliera Universitaria Integrata Verona (northern Italy) are invited to participate in the study. The researcher invites the parents to participate during the stay in the NICU, when the infant's medical condition has been stabilised: this usually happens around or after 32–33 weeks PMA; therefore, the recruitment of the study participants takes place from 32 to 34+6 weeks PMA. A minimum of 20 mother–infant and 20 father–infant dyads will be recruited. This sample size is adequate to perform parametric statistical tests, and is in line with the sample size of previous Italian studies47 ,58 ,69 ,70 in the field.

Parent–infant interaction in NICU

Between 34 and 35+6 weeks PMA, the mother's spontaneous social stimulation addressed to the infant in a cot with a radiant heater (an open cot with an overhead heating source) and the infant's responses are videotaped during a 3-minute interaction. Then the infant rests for at least 5 min. Afterwards, the father's social stimulation addressed to the infant and the latter's responses are videotaped over a 3-minute interaction. The date and timing for video-recording parent–infant interaction depends on: (1) the infant's medical conditions, (2) the mother's and father's restrictions on the time available to stay in the NICU, (3) the infant's behavioural states (for instance, if the infant is sleeping or crying the video recording is postponed).

Qualitative interviews in NICU

Previous studies that have conducted interviews with fathers of premature infants provide a coherent picture. The preterm birth of an infant is a traumatic event for the fathers,71 who have been found to show low/moderate levels of adjustment to preterm birth and a limited assumption of paternal role.72 Research also suggests that fathers experience a sense of lack of control.73 Often fathers hide these emotional difficulties from healthcare providers,25 ,74 but reported a need to share70 with someone who can understand.24 The first moments with the preterm infants evoke a ‘rollercoaster of emotions’75 which can lead fathers to become emotionally, and sometimes physically, distanced from the situation. After the initial shock and trauma, research has shown that fathers can experience emotional closeness27 with their infants during hospitalisation in the NICU.

Before the infant's discharge from the NICU, fathers are contacted to participate in a semistructured interview. The interviews allow for a deeper understanding of the emotional impact that the premature birth has on fathers. The topic guide includes the following areas: the first time that the father saw and/or touched his baby; the bond with the baby; caregiving activities; feelings associated with seeing the partner/mother care for, feed or cuddle their baby; space for one's own emotions when supporting and assisting the partner; work and management of their responsibilities in the outside world during the period of hospitalisation in NICU; the quality of the couple relationship during pregnancy and the period of hospitalisation in NICU; and how their feelings towards the baby change from his/her preterm birth to the time of discharge from the NICU.

In addition to the fathers who will participate in the parent–infant interaction, we will recruit an additional number of fathers who meet the inclusion criteria for parents and infants. These additional participants will not need to meet the infants' exclusion criteria. This will allow the study to have a more representative sample of daily clinical reality.

Interviews are carried out in a private room in the NICU, and are digitally recorded.

Questionnaires in NICU

In approximate times with videotaping, parents are asked to complete the Center for Epidemiologic Studies Depression Scale (CES-D)76 to assess symptoms of depression and the Dyadic Adjustment Scale (DAS)77 to assess the quality of the couple's relationship.

Parent–infant interaction after discharge

At 4 months CA, 3 min of mother–infant and 3 min of father–infant spontaneous face-to-face interaction are videotaped in the Social and Language Development Laboratory, University of Verona. The infant is seated in an infant seat on a table; the mother/father, seated opposite the infant, is asked to play with the baby as she/he would at home. Two video cameras are used to generate a split-screen view of the interaction.

Questionnaires after discharge

Parents are asked to complete the CES-D Scale and the DAS Scale again at 4 months CA, in order to assess symptoms of depression and the quality of the couple's relationship around 5 months after discharge from the NICU.

Further data on parents and infants

Data are collected on the parents' demographic and socioeconomic characteristics (age, marital status, years of formal education, occupation, family composition and social network), on the mothers' gynaecological and obstetric history, on their infant's neonatal characteristics (gestational age, weight, height and head circumference) and on the severity of the perinatal problems (evaluated using the Perinatal Risk Inventory; PERI)78 will be collected. Information are also collected regarding the infant's hospitalisation and developmental outcomes (assessed after discharge in a follow-up based on a paediatric examination including a somatic and neurological status assessment).

Video coding

Mother/father's and infant's behaviours from videotaped interactions are coded microanalytically, using units of 1 s.79–81 Parent and infant behaviours are coded independently in ordinalised scales required for performing time series analysis (see below).

With regard to parent–infant interactions in the NICU, both parent and infant behaviours are coded in composite categories of Engagement Scales, recently devised by Lavelli and Beebe:82 the Mother/Father Engagement Scale, ordinalised from a high of maternal affiliative behaviour45 (composed of ‘gaze at infant face + affectionate or static touch + affectionate talk and/or positive facial affect’) to a low of ‘gaze off’; and the Infant Engagement Scale, ordinalised from high levels of ‘gaze at parent face + smile’ and ‘gaze at parent face + active movements’ to a low of ‘negative expression’. Communicative modalities included in maternal affiliative behaviour have been described as the main components of the maternal postpartum repertoire in humans and as predictor of positive outcomes.48 Among these modalities, in the NICU context maternal/paternal static touch as firm and sustained touch47 is an effective and salient way to be in contact with the preterm infant, given the loss of physical contact with the mother and the prolonged separation that results from the NICU experience; therefore, otherwise that with full-term infants, static touch is not considered less optimal than affectionate touch.

With regard to parent–infant face-to-face interaction at 4 months CA, parents' behaviours are coded according to their gaze direction (on-off the infant's face); mother/father touch, ordinalised from a high of ‘affectionate’ to a low of ‘intrusive’ using the Maternal Touch Scale83 adapted to the Italian caregiving culture; mother/father facial affect, based on Beebe et al81 and ordinalised from a high of ‘mock surprise’ to a low of ‘negative’. Infants' behaviours are coded according to their gaze direction (on-off the infant's face); infant vocal affect, adapted from Beebe et al81 and ordinalised from ‘high positive’ to ‘angry protest/cry’; infant facial affect, adapted from Beebe et al81 and Lavelli and Fogel,15 and ordinalised from ‘high positive’ to ‘negative’.

The inter-rater reliability (Cohen's κ) for maternal/paternal/infant behaviours will be calculated on 20% of the videotapes, which will be coded by a second researcher who is blind to the aims of the study.

Quantitative data analysis

To explore the possible presence of early interactive contingency between parental communicative behaviours and infant gaze direction and expression (objective 1), a sequential analysis (conditional probabilities, GSEQ software)84 will be computed to examine the probabilities that the infant gazes at the parent's face with positive/neutral expression when the mother/father provides affiliative behaviour, and vice versa, that the mother/father provides affiliative behaviour when the infant shows to be engaged or ready for social stimulation. Furthermore, since the conditional probabilities analysis highlights specific associations of behaviours but not how any interactive contingency unfolds during the entire segment of videotaped interaction, a time-series modelling83 of the moment-to-moment sequence of behaviours will be performed to explore the parents and infants capability to coordinate their behaviours at any level of engagement versus disengagement across the videotaped session. Self-contingency will be computed as exploratory variable of the time-series analysis.

With regard to the second objective, that is, to assess whether higher engagement coordination (interactive contingency) between mother/father and preterm infant in the NICU predicts higher engagement coordination (interactive contingency) during parent–infant face-to-face interaction at 4 months CA, a multilevel time-series analysis83 will be performed. This analysis will allow to create indices of self-contingency (autocorrelation) and interactive contingency (cross-correlation) using the different possible pairs of parent–infant communication modality coded in behavioural scale (eg, infant gaze–mother/father gaze; infant vocal affect–mother/father touch, etc): these results will shed light on the process of mutual regulation during interaction at 4 months CA. Then, to assess the hypothesis that interactive contingency between parent and infant in the NICU is longitudinally related to the quality of their relationship at 4 months CA, it will be necessary to create an Infant Engagement Scale at 4 months, through an algorithm, as well as a Mother/Father Engagement Scale from their interaction at 4 months, in order to have behavioural scales which are comparable with those used for coding interaction in the NICU.

Finally, the hypothesis of early interactive contingency as a predictor of later mutual engagement will be also assessed by a linear regression analysis. A set of linear regression analyses will be performed using different study variables as possible predictors of quality in mother–infant and father–infant interactions at 4 months CA, in order to contribute to investigate the relationship between the different variables (objective 4).

Qualitative data analysis, and following mixed analyses

A thematic content analysis85 ,86 of the fathers' interviews will allow us to investigate the emotional impact of the premature birth on fathers (objective 3). To this aim, results will be integrated with field notes taken during ethnographic observation and results from the self-report instrument assessing symptoms of depression. All transcripts will be verified by one researcher before data analysis by listening to the audio recording and checking for accuracy of the written transcript. The transcripts will be analysed using a thematic content analysis for each question in the interview. Thematic analysis is a qualitative method for identifying, analysing and reporting themes within data.87 Transcripts will be read and reread so as to become familiarised with the data. Data will be managed using NVivo 11 (QSR International, USA). The first author will use an initial open coding to allow for the emergence of recurrent themes across fathers. Response patterns that will be relevant across all fathers will be coded and organised in thematic categories (along with verbatim quotes which illustrate each theme).87 ,88 All codes will be compared and contrasted, and then examined and discussed by the first author and two other researchers to identify meaningful categories or emergent themes. Codes with a single occurrence will be removed. Coding reliability and face validity achieved by remaining codes will be checked. A final coding scheme (defining each theme with verbatim quotes) will be collated. All transcripts will be recoded by the first author using the coding scheme. The inter-rater reliability will be calculated on 20% of the transcriptions, which will be coded by a second researcher.

A bivariate correlation analysis between theme frequencies emerging from the fathers' interviews, the scores questionnaires indexing symptoms of maternal/paternal depression and the quality of the couple relationship, the scores from the PERI78 and behavioural measures of quality in parent–infant interaction such as maternal/paternal affiliative behaviour, early interactive contingencies and mutual engagement at 4 months, will be performed to assess possible concurrent and predictive associations, and patterns of association, between study variables (objective 4).

Qualitative data will contribute to explain results from statistical analyses.