This study aims to improve how neonatologists check the heart function of newborn babies, especially those who are sick. While standard heart ultrasound scans are useful, a more advanced and sensitive technique called 2D speckle tracking echocardiography (STE) can detect subtle problems with how the heart muscle squeezes and relaxes. This may allow doctors to spot potential issues earlier.

Our research will take place at Birmingham Women's Hospital. The investigators will perform these advanced, non-invasive heart scans on several groups of babies:

1. Healthy term and premature babies, to establish a "normal" range of heart function.
2. Babies who are unwell with specific conditions, including those with brain injury due to lack of oxygen at birth (HIE), chronic lung disease of prematurity (BPD), a hole in the diaphragm (CDH), or high blood pressure in their lungs (aPHN).

The heart scan is a standard, painless procedure. Using STE does not require any extra scanning time or cause any additional discomfort to the baby; the special images are taken during the routine scan. For many of the sick babies, these scans are already part of their normal clinical care.

The main goals of this observational study are to see if STE is a feasible and reliable tool in newborns, to establish normal values for healthy babies, and to track how heart function changes in sick babies during their illness and recovery.

Ultimately, the investigators hope this research will provide doctors with a better tool to assess heart health in newborns. This could lead to earlier, more accurate detection of heart problems and help guide treatment decisions to improve outcomes for these vulnerable infants.

Inclusion Criteria:

• Neonates who are inpatient at the Birmingham Women's Hospital
• Confirmed diagnosis of acute pulmonary hypertension, congenital diaphragmatic hernia, hypoxic ischaemic encephalopathy, or bronchopulmonary dysplasia/chronic lung disease (defined by oxygen/respiratory support requirement at 36 weeks post menstrual/corrected gestational age).

OR

• Health control (>36 weeks - well and on the postnatal ward)
• Well preterm neonate (<36 weeks) admitted to the NICU, transitional care or post-natal wards.
• Informed consent obtained from parent(s) or legal guardian(s)

Exclusion Criteria:

• Presence of major congenital heart disease (other than patent foramen ovale or patent ductus arteriosus).
• Presence of other life-limiting congenital anomalies (other than CDH) or syndromes that could independently affect cardiac function.
• Inability to obtain adequate echocardiographic images for STE analysis after reasonable attempts.
• If the neonatal consultant or neonatal nurse caring for the neonate feels that the neonate is too unstable for inclusion in the study or that consent should not be sought from parents.

Inpatient status at Birmingham Women's Hospital Neonatal Unit - only babies admitted to the neonatal unit, transitional care ward or postnatal ward will be considered for screening.

Belong to one of the following target clinical groups:

• Group 1: Term neonates diagnosed with Hypoxic Ischaemic Encephalopathy (HIE) and receiving therapeutic hypothermia.
• Group 2: Preterm neonates born at or before 32 weeks' gestation, who are later diagnosed with Chronic Lung Disease (CLD) requiring supplemental oxygen at 36 weeks corrected gestational age.
• Group 3: Term neonates diagnosed with Congenital Diaphragmatic Hernia (CDH).
• Group 4: Term neonates diagnosed with Acute Pulmonary Hypertension of the Newborn (aPHN), excluding those with CDH.
• Healthy controls:
• Term neonates (>36 weeks' gestation) who are well and on postnatal wards.
• Well preterm neonates (<36 weeks' gestation). • Stable enough for echocardiography and research inclusion, as determined by the attending physician.

The REC required removal of the proposed wording allowing anonymised participant data to be shared with external researchers on request. As participants are not being consented for future research data sharing, the study has no plan to share IPD, and the ClinicalTrials.gov IPD field is therefore recorded as "No". This is an observational trial with no intervention and not a clinical trial of a device or drug.