Rehema Figueiredo and Ben Wilkinson

London - The seven-year itch is a real phenomenon backed up by cold hard facts, according to an academic.

There has long been a superstition that the milestone marks the make-or-break point in a relationship.But Cambridge University statistics professor Sir David Spiegelhalter says that data actually backs up the theory – as couples are most likely to divorce after seven years of marriage.

He also said that if couples make it past that point, the likelihood they will break up falls year on year after that.

Speaking at Hay Festival, Sir David said: “For those who have been married 15 years, about one-and-a-half per cent will end in their 16th year. Seven years is the peak risk time for divorce during a marriage.”

Sir David, who was recently elected as president of the Royal Statistical Society, said that while you might expect there to be another peak in divorces later in marriages, data from the Office for National Statistics (ONS) shows this is not the case. He added: “[The risk of divorce] just steadily declines as we get used to each other. It’s a four-star statistic, the seven-year itch.”

Sir David said it still applies even though more couples are living together for three or four years on average before getting married.An ONS report in 2012 showed that the likelihood of a couple divorcing before their next anniversary increased steadily during the early years of marriage and peaked at 3.25 percent around a couple’s seventh anniversary. It then gradually decreased again afterwards.The seven-year itch got its name from a play of that name by George Axelrod which was turned into a hit film starring Marilyn Monroe.

For years scientists have tried to find explanations for why the phenomenon might happen.

In the 19th century Austrian philosopher Rudolf Steiner suggested humans change physically and mentally every seven years and so are more likely to grow apart from each other.

But there has been much debate about whether the seven-year itch actually exists.

In 1999 Dr Larry Kurdek, a psychology professor at Wright State University in Ohio, found evidence for a dip in affection after four years and again after seven years of marriage. But last year a British study suggested the real test is the first anniversary, when a man’s testosterone levels, the key to his sex drive, plummet.

Sir David was speaking at the festival to promote his latest book, Sex by Numbers: What Statistics Can Tell Us About Sexual Behaviour, which came out last year.– Daily Mail