On the long and winding road to having it all, Helen Parker is making good progress. At 27 she’s forging a career as an executive with a transport company in London, she has a steady boyfriend, and together they are buying a flat. One day the prospect of starting a family will beckon.

By many standards, she’s thriving. So is she happy?

“Um, I’m reasonably happy,” she said. “And I’m optimistic about the future. But there will always be sacrifices.

“There’s plenty more opportunities for women than there used to be — but then again, that means you are always questioning whether the moves you have made are correct, or whether you should have done something else.”

Like many women, her sense of wellbeing and life satisfaction do not match up with advances in social circumstances and material comforts. After 40 years of fighting for equality, it seems that women are no happier. In fact, women in many countries have been growing steadily unhappier compared with men, according to a study published this month by the National Bureau of Economic Research in the United States.

In The Paradox of Declining Female Happiness, Betsey Stevenson and Justin Wolfers of the University of Pennsylvania, begin by noting the gains.

“By many measures the progress of women over recent decades has been extraordinary: the gender wage gap has partly closed; educational attainment has risen and is now surpassing that of men; women have gained an unprecedented level of control over fertility; (and) technological change in the form of new domestic appliances has freed women from domestic drudgery,” they wrote.

Yet Stevenson and Wolfers have found that in America women’s happiness, far from rising, has fallen “both absolutely and relatively to that of men”. Where women in the 1970s reported themselves to be significantly happier than men, now for the first time they are reporting levels of happiness lower than men.

In Europe, people’s sense of happiness has risen slightly, but less so for women than men. In 12 European countries, including Britain, the happiness of women has fallen relative to that of men.

The authors readily admit that measuring happiness is necessarily a subjective task, but the overall trend from the data, compiled from social surveys conducted over many years, is clear and compelling.

The work builds on earlier research by Andrew Oswald, professor of economics at Warwick University, who has a particular interest in the study of happiness. He said: “What Betsey and Justin have done, which is a valuable addition, is to show that the trend is found rather widely. For most of the post-war era, happiness surveys showed women noticeably happier than men. That difference has now eroded to zero.”

The big question is: why?

Times Recommends

• Please help: maimed children of war want their lives back
• Cabal seizes diamond riches to buy power
• White House gatecrashers got to the president