Forget natural resources, sound economic management or trade deals – sex is the thing to save Denmark’s future.

That’s according to a risqué new ad campaign by Spies Travel that encourages young Danes to go on holiday and make babies.

And nothing is off-limits in the ad, which implores mothers to pay for their children’s sex-filled holidays.

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Despite the cheekiness of the ad, it taps into real issues facing the country.

In September The Guardian published a report on a tumbling birth rate in the Scandinavian country.

“Denmark’s birth rate is just 1.9 – it should be 2.1,” it said.

“So we need to educate men that if they want children, they need to get on with it while their partner still has time,” a public health professor from Copenhagen said.

Mum sneaks into the bedroom, to help remove a bra in the ad. Photo: YouTube

In 2013, the birth rate was 10 per 1,000 Danish people, a 27-year low according to the campaign.

“If they won’t do it for their country, surely they will do it for their mother,” the ad says.

The ad, called Do it for Mum, begins by saying: “You can’t buy love – or can you?”

“The Danish welfare system is under pressure. There are still not enough babies being born, despite a little progress. And this concerns us all.

“But those who suffer most are perhaps the mothers who will never experience having a grandchild.”

It is aimed at wannabe grandmothers, in an attempt to make them contribute money to their children’s holidays with partners.

The hope is that on holiday, the couples will have babies, and within nine-months deliver grandchildren to the parents.

That is a sound return on the economic investment in the holiday, the ad argues.

But like one scene from the ad, where a Mum lingers in the bedroom to remove the bra of a romping couple, things go a little too far.

Spies Travel argue studies show that Danes have more sex on holiday, because they’re happier and more active. Approximately 51 per cent more likely in fact.

A webpage created for parents to share with their kids gives some very explicit tips too.

While this one gives various hotels a “conception indicator” rating.

Spies Travel does have form in the baby-making stakes.

Last year it spawned a similar campaign called “Do it for Denmark”, which implored young Danes to: “Book your holiday with an ovulation discount”.

But Do it for Mum extends the advice to workout inspiration : “As you may already know, people have more sex on a sunny vacation.

“But what you might not know is exercise with your partner increases the sex drive even further because the brain releases endorphins.”

Cue a shot of a sweaty and puffed out couple lying next to each other on the floor of a gym.