Can you predict a recession by looking at pregnancy rates?

The rate of women becoming pregnant begins to fall several months before the start of a recession, new research from US academics suggests.

Its authors said fertility rates might help predict economic downturns.

They were more accurate than some traditional indicators, they said.

The research shows the rate of conceptions stopped increasing and began to fall several quarters before the start of the last three recessions in the United States.

Economists are frequently criticised for failing to accurately predict the direction of economic growth. Increasingly they are looking beyond traditional measures such as manufacturing output, retail spending and house prices to help build a more complex and accurate picture.

"We think that the factors behind the last three recessions also had a profound and rapid effect on fertility decisions," the report's authors said, summarising their findings.

"In fact, these factors seem to have impacted fertility decisions before large parts of the economy."

The authors of Is Fertility a Leading Economic Indicator? tracked more than 100 million births in the United States between 1989 and 2016. They incorporated data on miscarriages and abortions.

It was already accepted that birth rates fall as consumer confidence falls but Daniel Hungerman, Kasey Buckles and Steven Lugauer show for the first time that conception rates nine months earlier suggest a change in sentiment before other signs are visible.

"The growth rate of conceptions declines very rapidly at the beginning of economic downturns and the decline starts several quarters before recessions begin," the paper said.

The paper says for example that in December 2007 a poll of busi- ness leaders found they were optimistic about the future, although it later transpired that by then the recession had begun.

At that point the growth in conception rates had already been falling for several months, with the decline starting several quarters before the collapse of Bear Stearns and Lehman Brothers.

There's also a correlation with the scale of the downturn.

Fertility sank more rapidly (by four percentage points) before the deeper 2007 recession than in the run up to the two previous dips in the early 1990s and the early 2000s.

Increasingly the collection of vast amounts of detailed data on everything from online searches to shopping and eating patterns is allowing economists to explore new sources of information on the economy.

While it may not be simple to track conceptions, the report's authors suggested proxy data like the sale of fertility and pregnancy related goods could be monitored.

In a much reported case several years ago, the American retailer Target reportedly issued money off coupons on baby items to a teenager after mining its sales data and identifying she was pregnant.

The academics also looked at what happened to conceptions at the end of the last three recessions. But they found the data was less clear cut. The end of the 20072008 recession was dubbed a "jobless recovery". Hungerman, Buckley and Lugauer found it was also a "baby-less recovery."