This is an observational study in newborn term and preterm infants. The study will validate if non-invasive continuous cardiac output monitoring is feasible in newborn infants, if normative values can be constructed and what is the effect of fluid boluses and inotropes on cardiac output and peripheral vascular resistance.

This is a 3-year prospective observational study.

Principal research question:

Is non-invasive continuous cardiac output (CO) measurement a validated tool of comprehensive cardiovascular assessment in neonatal intensive care (NICU)?

Secondary research questions:

1. Can robust normal ranges of CO be constructed for neonates undergoing cardiovascular measurement?
2. How do neonatal interventions (fluid boluses, ventilation and inotropes) affect CO?
3. Does the Non-invasive continuous cardiac output monitoring in children with foetal growth restriction (FGR) differ from normative CO data as above (1)?

A prospective study of stable newborn babies in the postnatal ward and sick term and preterm infants in the NICU in 36 months.

Inclusion Criteria:

• Healthy term infants in postnatal ward (within the first 72 hours of age)
• Term and Preterm infants (including those with FGR) admitted to the neonatal unit
• Written informed parental consent (prospective for postnatal ward and retrospective for babies admitted to the neonatal units)

Exclusion Criteria:

• Antenatal or postnatal diagnosis of severe congenital anomaly
• Infants with no realistic chance of survival
• Infants who are >12 hours of age
• Infants with fragile skin not permitting skin probe placement

All term and preterm infants (24-42 weeks of gestational age) for the validation study and preterm infants with fetal growth restriction for the longitudinal study.