Three saliva samples will be collected from each subject, at 8:00, 15:00 and 23:00 hours. Before collecting the saliva they will be instructed to rinse their mouth with cold water, without brushing their teeth. They should also not eat or drink in the hour before the sample is taken. Approximately 1 ml of saliva, collected by direct expectoration into an ependymal tube, shall be obtained and the samples shall be stored for 24 hours at 4°C . Subsequently, samples shall be centrifuged at 2 500 rpm/10 min and the supernatant shall be stored at -20 °C until processing by ELISA kit as per the above protocol.

The treatment and collection of saliva as a biological sample shall be identical to the protocol described for the determination of cortisol. The determination of oxytocin shall be carried out by the use of ELISA kit for immunoassay (Oxytocin ELISA Kit (ab133050 ABCAM)

They are a set of three standardised assessment scales, which assess the cognitive, motor and language development of children aged 1 and 42 months. For our study, we will use only the motor scale, which is composed of two subscales, the gross motor scale and the fine motor scale. This motor scale is composed of 138 items (the gross motor scale is composed of 72 items and the fine motor scale of 66 items) which assess the degree of control of the body, the coordination of large muscle masses and the manipulative ability of hands and fingers. The total administration time of the motor area for 12-month-old children, as in the case of the sample, is between 15 and 20 minutes.

The Strange Situation is a standardised observational procedure in which the child is exposed to two moments of separation from his/her attachment figure, two moments of reunion with the attachment figure and moments in which he/she interacts with an unknown person, specifically 8 episodes (lasting 3 minutes) in which the level of stress provoked in the child increases in intensity as the situation progresses. It is estimated to last around 20 minutes. It is assessed on a 7-point Likert-type scale, so that low scores indicate low frequency and intensity of the behaviour. These responses allow us to identify three types of attachment: secure attachment, insecure-avoidant attachment and insecure-ambivalent attachment. The strange situation only allows us to assess attachment in children between 1 and 2 years of age.

It assesses the stress experienced in parenting through several subscales such as parental distress, dysfunctional parent-child interaction and whether the child is a difficult child based on how parents perceive their children's behaviour.

- The Perinatal Risk Inventory is a measuring instrument that provides information on the neonatal situation prior to discharge and facilitates an estimate of the biological risk that the child may present from a very early age. The factors that are analysed in this inventory are evaluated with a score from 0 to 3 for each of the factors mentioned above, ranging from a minimum of 0 points to a maximum of 51. The levels of risk were determined as follows:

1. Low Neonatal Risk: 0 to 6 points.
2. Moderate Neonatal Risk: 7 to 9 points.
3. High Neonatal Risk: 10 or more points.

is an assessment technique that provides a profile of scores that allows us to detect a possible alteration or pathology, but at the same time, within normal parameters, to detect both the potential or 'strong points' and the problems or 'weak points' of the newborn, as well as their peculiar ways of acting and reacting to environmental variables. Therefore, a profile of the child's behavioural characteristics is obtained, which can be considered as a first outline of the child's temperamental traits. It evaluates the behavioural repertoire of the newborn in 28 behavioural items that are assessed according to a 9-point scale. The scale also includes an assessment of neurological status in 18 reflex items, each with a 4-point rating. In the second edition of the NBAS a series of 7 supplementary items were added with the intention of better capturing the degree of fragility and the quality of behaviour of high-risk children.

Galvanic Response: has the function of measuring the galvanic response of the skin, also known as electrodermal activity (EDA). It is used to record the electrical behaviour of the skin, which varies according to the activity of the sweat glands. This measurement of electrodermal activity is essential for studying the activity of the autonomic nervous system, which controls involuntary body functions such as sweating and heart rate. It will be measured with the BIOPAC MP36R device.

ECG is used as a monitoring target for various cardiovascular conditions. It will be measured with the BIOPAC MP36R device.

P, Q, R, S, T, U waves; QRS complex, PR interval and QT interval and PR segment and ST segment.

The transducer is attached to a strap that is placed around the subject's chest, allowing chest movements to be detected during breathing. The strap ensures a secure and comfortable fit for the subject during the measurement process. This transducer is used in conjunction with other BIOPAC components to assess physiological responses. The data obtained from the transducer provides information on respiratory patterns and their relationship to other physiological measures. It will be measured with the BIOPAC MP36R device.

PSI-SF is a 36-item, self-report measure of parenting stress. It includes three subscales: Parental Distress (PD; e.g, "I feel trapped by my responsibilities as a parent", "I feel lonely and without friends"), Parent-Child Dysfunctional Interaction (PCDI; e.g, "Sometimes I feel my child doesn't like me and doesn't want to be close to me", "When I do things for my child I get the feeling that my efforts are not appreciated" ), and Difficult Child (DC; e.g, "My child makes more demands on me than most children", "My child gets upset easily over the smallest thing"). Each subscale consists of 12 items rated from 1 (strongly disagree) to 5 (strongly agree), with subscales scores ranging from 12 to 60. A Total score is calculated by summing the three subscales scores, ranging from 36 to 180. Scores of 90 or above may indicate a clinical level of stress. Cronbach's alpha coefficients of .91 for PSI-SF total score, and .87, .80, and .85 for PD, PCDI, and DC subscales.

It consists of a total of 18 risk factors such as 1) Apgar score; 2) electro-encephalogram; 3) non-metabolic seizures; 4) intraventricular haemorrhage; 5) hydrocephalus; 6) neurological findings (not for hydrocephalus or HIV); 7) gestational age at birth; 8) weight for gestational age; 9) dysmorphias; 10) assisted ventilation; 11) cranial growth (children hospitalised 6 or more weeks); 12) cranial growth (children hospitalised less than 3 weeks); 13) polycythaemia; 14) meningitis; 15) hypoglycaemia; 16) congenital infections; 17) hyperbilirubinaemia; and 18) associated medical problems (not central nervous system). These factors are assessed with a score from 0 to 3 for each of the above factors, ranging from a minimum of 0 points to a maximum of 51 points. Risk levels:

1. Low Neonatal Risk: 0 to 6 points.
2. Moderate Neonatal Risk: 7 to 9 points.
3. High Neonatal Risk: 10 or more points.

It evaluates the behavioural repertoire of the newborn in 28 behavioural items that are assessed according to a 9-point scale. The scale also includes an assessment of neurological status in 18 reflex items, each with a 4-point rating. The NBAS can be used without any adaptations for full-term children and can be used until the end of the second month of life. With the addition of supplementary items it can also be used with apparently healthy preterm infants (less than 37 weeks gestation) and for them, depending on the degree of immaturity, application is possible up to 48 weeks post-conceptional age. <7 points: low, suggests newborn distress requiring intervention.

7-9 points: normal. child in good health.

They are a set of three standardised assessment scales, which evaluate the cognitive, motor and language development of children aged 1 and 42 months. We will use only the motor scale, which is composed of two subscales, the gross motor scale and the fine motor scale. This motor scale is composed of 138 items (the gross motor scale is composed of 72 items and the fine motor scale of 66 items) which assess the degree of control of the body, the coordination of large muscle masses and the manipulative ability of hands and fingers. The total administration time of the motor area for 12-month-old children, as in the case of the sample, is between 15 and 20 minutes. average motor score: 100; <85=mild impairment; <70=moderate-severe impairment

The Strange Situation is a standardised observational procedure in which the child is exposed to two moments of separation from his/her attachment figure, two moments of reunion with the attachment figure and moments in which he/she interacts with an unknown person, specifically 8 episodes (lasting 3 minutes) in which the level of stress provoked in the child increases in intensity as the situation progresses. It is estimated to last around 20 minutes. It is assessed on a 7-point Likert-type scale, so that low scores indicate low frequency and intensity of the behaviour. These responses allow us to identify three types of attachment: secure attachment, insecure-avoidant attachment and insecure-ambivalent attachment. The strange situation only allows us to assess attachment in children between 1 and 2 years of age.