Congenital heart defects (CHD) are the most common congenital malformations. If diagnosed late, babies can become extremely unwell with long-term implications for health and neurodevelopment. CHD can be detected before complications arise through a simple non-invasive screening test using pulse oximetry. Some countries have introduced national screening programmes. This project will address whether a national screening programme for CHD should be introduced within the unique New Zealand maternity setting. We will determine the feasibility of universal pulse oximetry screening within NZ and will determine: cost-effectiveness; acceptability to parents and their families; impact upon maternity care providers’ work-load; the cost and burden of false-positive and false negative results, and the uptake of screening by maternity health professionals and families. The outcome of the project will be evidence-based recommendations to the Ministry of Health to inform policy and national health care investment.