In this project, the investigators will study a cohort of preterm infants, together with their parents, during NICU hospitalization and follow their developmental trajectory until the age of two.

An important first scientific goal of the project is to identify objective stress markers that can be obtained easily and non-invasively in preterm infants during NICU hospitalization. This will include the development of novel techniques to measure stress related heart rate variability (HRV) and EEG maturation, as well as sleep stage markers for preterm infants.

Secondly, the investigators will study the emotional and bonding processes in parents of preterm infants. Parental distress in terms of depressive symptoms, anxiety, perceived stress and parent-infant bonding will be measured at multiple measuring points. This will enable the validation of psychometric instruments in the specific population of parents of preterm infants. Also, the investigators can investigate the effect and predictive value of the course of parental depression, anxiety and stress scores on child's developmental outcome and on parent-infant bonding and attachment.

Thirdly, studies on epigenetic changes due to prenatal stress are still scarce in humans. In this study, the investigators will include a cohort of mothers experiencing profound prenatal stress due to preterm labor, which will complement the earlier work that has been carried out in a low-risk population. The investigators expect more profound changes in methylation state of the NR3C1 and other promotor regions in their cohort of mothers exposed to important prenatal stress. Secondly, the methylation of oxytocin receptor regions will be studied in relation to attachment and bonding.

An important overall goal of the project is to develop a Perinatal Stress Calculator that studies the value of the different neonatal, endocrinological, psychological and physiological stress-related parameters to predict differences in psychomotor, cognitive, behavioral, and emotional development. This longitudinal study design will enable the investigators to use the perinatal stress calculator to study the relation between the perinatal stress parameters and later developmental disabilities such as motor impairment, cognitive deficits, language delay but also social and behavioral problems such as attentional deficits and emotional self-regulation dysfunction.

Project goals and their impact on societal challenges:

Objective 1: The first goal of the project is to identify objective stress markers that can be obtained easily and non-invasively in preterm infants during NICU hospitalization. This will include the development of novel techniques to measure stress related heart rate variability (HRV) and EEG maturation, as well as sleep stage markers. On a societal and economical level, reliable measures of the degree of distress in a hospitalized preterm infant will enable the evaluation of the direct effects of stress-reducing interventions such as NICU architecture changes and early intervention programs in cost benefit analyses. (Work package 1)

Objective 2: Second, the investigators aim to study the emotional and bonding processes in parents of preterm infants. Parental distress in terms of depressive symptoms, anxiety, perceived stress and parent-infant bonding will be measured at multiple time points. This will lead to the validation of psychometric instruments in the specific population of parents of preterm infants. Also, the investigators will investigate the effect and predictive value of the course of parental depression, anxiety and stress on children's developmental outcome and on parent-infant bonding and attachment. Knowledge about the short and long term risks of parental emotional distress are important to implement sufficient and tailored support to parents. (Work package 2)

Objective 3: Third, studies on epigenetic changes due to prenatal stress are still scarce in humans. Recently, preliminary evidence was found that prenatal stress affects the methylation state of the NR3C1promotor regions (Hompes et al., 2013). In this study, the investigators will include a cohort of mothers experiencing profound prenatal stress due to preterm labor, which will complement the earlier work that has been carried out in a low-risk population. The investigators expect more profound changes in methylation state of the NR3C1 and other promotor regions in this cohort. The methylation of oxytocin receptor genes will also be studied in relation to attachment and bonding. On a societal level, knowledge about the impact of adverse maternal psychological well-being during pregnancy on the epigenome is important, for example to justify prevention campaigns. (Work package 3)

Overall objective: An important overall goal of the project is to develop a Perinatal Stress Calculator that combines the values of the different neonatal, endocrinological, psychological and physiological stress-related parameters to predict differences in psychomotor, cognitive, behavioural, and emotional development (Work package 5). This prospective longitudinal study design will enable the investigators to use the perinatal stress calculator to study the relation between the perinatal stress parameters and later developmental disabilities such as motor impairment, cognitive deficits, and language delay but also social and behavioural problems such as attentional deficits and emotional self-regulation dysfunction (Work package 4). The investigators will not only be able to weigh perinatal infant characteristics in the model, but also parental characteristics such as distress, resilience and personality as well as bonding and attachment measures. On a societal and economic level, the results of the project will be important for health policy decision-making. Improved prediction of the developmental trajectory of preterm infants could lead to earlier and targeted interventions to decrease maladaptive outcomes.

Inclusion Criteria:

• Preterm infants born before 34 weeks gestational age and/or with a birth weight lower than 1500g and their parents

Exclusion Criteria:

• Age < 18yr.
• Unable to speak and understand Dutch, French or English
• Unstable medical (somatic and/or psychiatric) disease in the parent(s)
• The presence of a major congenital malformation in the preterm infant

The investigators will approach parents of preterm infants born before 34 weeks gestational age and/or with a birth weight lower than 1500g.

Ideally, pregnant women admitted to the maternal intensive care (MIC) for preterm labor will be informed about the study together with their partner, and asked for consent. But in a number of preterm infants prenatal inclusion will not be possible (e.g. birth in another hospital, preterm premature rupture of the membranes,…) . Parents of infants in this subgroup, who are admitted to the Neonatal Intensive Care Unit (NICU) at the University Hospitals Leuven, will be informed and asked for consent within 3 days after birth.