Addictive television box sets such as Game of Thrones are stopping couples having as much sex as previous generations, a leading statistician has warned.
The trend of declining sex rates over the past 30 years was "very worrying", said David Spiegelhalter.
In 1990 couples made love about five times a month on average but by 2010 it was just three times. If trends continue, by 2030 couples will have stopped having sex all together, he said.
Previously researchers have warned that lovers are killing the mood by taking their iPads to bed.
But Prof Speigelhalter, Winton Professor of the public understanding of risk at Cambridge University, blamed the rise of "massive connectivity" embodied by streaming services such as Netflix, smartphones, and television box sets.
Speaking at the Hay Festival, which is sponsored by the Telegraph, he said: "How many times have you had sex in the last four weeks? You can start seeing the changes in society.
"People are having less sex. Sexually active couples between 16 and 64 were asked and the median was five times in the last month in 1990, then four times in 2000 and three times in 2010.
"At this rate by 2030 couples are not going to be having any sex at all. Which is a very worrying trend.
"You say 'Why?' Statisticians say 'I don't know'. One of the researchers mentioned the word iPad.
"I think it's the box set, Netflix: 'OMG I've got to watch the entire second series of Game of Thrones'.
"The point is that this massive connectivity, the constant checking of our phones compared to just a few years ago when TV closed down at 10.30pm or whatever and there was nothing else to do.
"Even power cuts, which helps. Now people are having less sex."
Prof Speigelhalter also said couples who had sex more often were more likely to have boys, as statistics showed getting pregnant earlier in the ovulation cycle favoured male children.
It is why there is often a big surge in the birth of boys at the end of wars when soldiers return home and are having increasing amounts of sex.
Prof Spiegelhalter added: "If you're having a lot of sex then it's more likely you'll get pregnant before the time of peak fecundity. There is some evidence from animals that there is a very small increased chance of having a boy if you conceive earlier. Don't use this choice as a sex choice method, it only works at population level.
"What happens at the end of wars is demob and home on leave. A time of intense sexual and unprotected activity is at the end of wars." Fertility rates rose in Britain at the end of the Second World War until the invention of the Pill, when they began to plunge.
There was a surprise peak in 1973 which he said might be traced to the then oil crisis and the resulting three-day week and power cuts.
The Daily Telegraph