But Auckland obstetrician Dr Sue Belgrave, who chairs a national committee on maternal mortality, said the country's high death rate for women in pregnancy and childbirth of 15 deaths for every 100,000 live births was because New Zealand's figures included deaths from pre-existing conditions and suicide.
"I'm not saying we are perfect, but what we report is an accurate reflection of what is happening in our system. We don't think that's happening in other countries," she said.
New Zealand ranked in the bottom half of the 130 countries for suicide (76th behind the best) and obesity (115th).
But other countries also had low scores on enough indicators to drag them below New Zealand's overall tally of 88.24 out of a maximum score of 100.
Switzerland was close behind with 88.19 points, followed by Iceland, the Netherlands and Norway. Australia came tenth with 86.10 points.
The United States was 16th with 82.77 points, scoring in the bottom half on ecosystem sustainability (69th) and on health and wellness (70th), again partly because of a high obesity rate.
The index is the latest of many attempts in recent years to develop better measures of national wellbeing than the traditional gross domestic product (GDP), which has been widely criticised for measuring only what can be counted in dollars.
For example, New Zealand's measured GDP is rising rapidly at present partly because of the Christchurch rebuild, but the destruction of the previous buildings in the the 2011 earthquake did not count as reduced GDP.
Professor Porter is widely known for his books on international competitiveness, including a 1991 report on New Zealand's competitiveness which advocated fostering "clusters" of internationally competitive firms.
Think-tank director Michael Green, a London-based economist and author of Philanthrocapitalism: How Giving Can Save the World, said New Zealand's placing as the world's most socially advanced nation contrasted with its 25th place in GDP per person.
"In terms of converting economic output into quality of life, New Zealand is doing really well," he said.
AUT sociologist Professor Charles Crothers said he had long thought New Zealand's low GDP rating was "a bit weird".
"We have quite a low GDP per capita in the OECD ranking, but the reality of living in New Zealand is beyond what it looks like in the standard of our homes, education, health and so on. We are firing well above that," he said.
He said it was surprising that Professor Porter's index left out indicators such as the employment rate and income inequality, but it was a fair reflection of the things it did measure.
"There are no nasty divisions," he said. "We are a happy enough lot of hobbits just tagging along without any extreme hatred or violence."
Social Development Minister Paula Bennett said: "This report is great news and it backs up what we all know - that we live in a fantastic country."
Labour social development spokeswoman Sue Moroney said New Zealand's high scored reflected "Labour's progressive agenda" in building up public health and education over many decades.
