Assessment of the physiological effects of Kangaroo Care in preterm infants.

Throughout the literature there is consensus about the importance of adequate
bonding between parent(s) and infant. Currently, bonding is defined as a
process of co-regulation. This means that during bonding, the one organism
supports (co-regulates) the other with regulating his / her internal
environment. This co-regulation ensures that the infants' valuable energy
resources are efficiently used; regulating the internal environment costs less
energy when assisted by a caregiver. In the case of the parent-infant, and
especially the mother-infant bond, physical maternal aspects (such as body
heat, heart rhythm, voice and touch) help the baby stabilize their internal
environment. A lack of maternal contact interferes with this stabilisation and
thus with optimal (neuro)development; more energy is required for the infant to
regulate his / her environment, so less energy can be used to grow and thrive.
Being born premature leads to a necessary Neonatal Intensive Care Unit (NICU)
or Medium Care (MC) admission. For medical and practical reasons, parents can
then spend less time with their infant as they would actually want. Let alone
time spent in physical contact.

In order to compensate for this negative consequence of prematurity, throughout
the hospital admission Kangaroo Care (KC) is stimulated as part of the routine
therapy. Research has demonstrated that KC is a period of optimal
co-regulation. KC is when the baby is naked and is held to the naked parental
chest in a supine position. The reported positive effects are better scores on
neurodevelopmental scales, shorter hospital stays, increased weight gain, less
infections, less bradycardias and less apneas.

According to the literature, oxytocin and vasopressin are the most important
hormones for the complex mechanism that enables co-regulation. Oxytocin is
important for the imprinting of certain scents, breastfeeding and sucking
mechanisms. These are all very important aspects for the infant's growth.
Furthermore, oxytocin influences neurodevelopment. It affects cortical
development and the development of the limbic system. Globally, oxytocin is
seen as the most dominant regulator for positive social interactions, whereas
vasopressin is more dominant in regulating agressive / protective social
behavior. Our hypothesis is therefore that oxytocin and vasopressin
concentrations change during KC, which causes preterm baby's to be maximally
comfortable. In adults, both hormones can be measured in a minimally invasive
way, namely in saliva. Oxytocin salivary concentrations appear to correlate
with plasma concentrations and cerebral spinal fluid concentrations. Peripheral
vasopressin however is highly dependent of the fluid balance, since fluid
regulation is vasopressin's main function. Measuring oxytocin in saliva in
different social situations is therefore the most interesting. Currently, much
research is undertaken measuring salivary oxytocin in adults and young infants.
In a pilot, we have established that it is also possible to measure the
co-regulation bio-marker oxytocin in preterm infants' saliva. It was possible
to do a power calculation with the oxytocin measurements from the pilot study.
This power calculation was based on our research question: Does KC cause a
significant increase in the salivary oxytocin concentration in preterm infants?

Demonstrate whether or not KC causes a significant increase in salivary
oxytocin concentration in preterm infants.

By gaining more insights into the biological processes that cause the positive
effects of KC, we can develop technologies that can be a KC surrogate within
the incubator in the future, to provide extra comfort at times when parents are
not able to be present.

Observational design wherein the salivary oxytocin concentrations from 21
prematurely born twins before KC are compared to their saliva oxytocin
concentrations during KC. The saliva before KC and during KC are collected at
an equal amount of minutes after the last feeding, to ensure that we do not
measure the effect of the feeding, but of the social interaction itself.
Regarding the very quick production of oxytocin after social interaction, the
saliva can already by validly collected after 15 to 20 minutes KC. Oxytocin has
a half life of 2-6 minutes, so measuring it after KC would be less valid than
measuring during KC.

For the power calculation, exact methods and procedures, see the study
protocol.

In total, participants will suck on cotton balls for approximately ten times
ten minutes. This is an overestimate. There are absolutely no risks to be
expected.