A documentary examines the link between diseases linked to the immune system, such as Type 1 diabetes and asthma, and modern birth methods.

A major documentary film being shown around the world examines how modern birth practices could be making our children more susceptible to disease later on in life.

Microbirth, produced and directed by Brighton film-makers Toni Harman and Alex Wakeford, highlights the rise in non-communicable diseases linked to the immune system, such as Type 1 diabetes, Crohn's disease, asthma and cardiovascular disease, and asks about the possible reasons for the increase.

Professor Stefan Elbe, director of the Centre for Global Health Policy at the University of Sussex, is among scientists from the UK and North America issuing stark warnings in the film.

Figures produced by the World Economic Forum and the Harvard School of Public Health predict that the cost of treating these diseases - which the World Health Organisation says causes 80 per cent of deaths worldwide - could bankrupt global healthcare systems by the year 2030, according to Prof Elbe.

"To put that into context, the combined economic output of most countries in the world any given year is less than one trillion US dollars and they are estimating a cost of 47 trillion US dollars. It is a staggering sum indeed," Prof Elbe said.

The film explores possible explanations for the rise in these diseases, including the hypothesis that births by caesarean section can interfere with the natural transference of hormones and good bacteria between mother and child, and profoundly affect the baby's immune system and metabolism.

While the scientists debate the medical and microbiological arguments, Prof Elbe warns of "the deeper threat to national security" of the rising tide of non-communicable diseases.

"If we don't find ways of managing for these diseases better, if we can't come up with cheap or cost-effective ways to address them, we are going to be landed with quite a big socio-economic problem that could be destabilising in the worst-case scenario," he said.

"So I think that's why we need to raise more awareness around non-communicable diseases and get more co-ordinated action on this.

"I don't think we are too late but we are definitely not too early either."

Prof Elbe warned society needed to change its thinking and confront the issue urgently, describing it as a "really big challenge".

Copyright AAP 2014.