As Travel agency offers three years' free baby supplies for couples who can prove they conceived on holiday

The bold Do it for Denmark advert, from Spies Rejser travel, promises three years of free baby supplies and a child-friendly holiday for the lucky couple who can prove they conceived their child while on one of their holidays.

The travel company claims it is tackling the country's declining birth rate by asking Danes to 'do it for Denmark' and reproduce.

A report published in February 2013 described the birth rate among Danish women as "dangerously low". It found more than one in five couples were childless, despite the majority of couples reporting wanting between two and three children, according to the Copenhagen Post.

Many couples are waiting longer to have children and there are fewer women of child-bearing age, the report states, leading to concerns that there will not be enough people to support an ageing population.

Spies' promotion highlights statistics (which are impossible to verify) that ten per cent of all Danes are conceived on holiday – and 46 per cent have more sex while away.

A sex therapist also explains that couples are more inclined to have sex while taking a break together because their desire for each other increases.

The competition even provides useful tips for increasing fertility, such as: "take advantage of gravity. Lie down for at least 15 minutes after sex", while advising men to avoid wearing tight pants "even if you think it looks good".

The competition website provides a list of romantic cities and asks entrants to enter the start date of their last period to find the time when they can take a trip while at their most fertile.

Jan Vendelbo, the managing director of Spies, said they wanted to make reproducing "even more fun" by offering discounts on city breaks "to help with population growth".

According to the terms and conditions, entrants are then sent a pregnancy tester kit after the holiday. If the result is positive, they are asked to send in a picture of the tester to Spies as proof of their conception.

“But if doing it for Denmark isn’t motivation enough,” the advert explains, “we made a little competition.”

“Book your holiday with your ovulation discount, get it on, and prove you conceived a child to win a three-year supply of baby stuff and a child-friendly holiday.

“But what if you already did your duty? Or what if your chance of conceiving a child isn’t so high?" it asks.

“Well look at it this way. It’s not jut about winning. All the fun is in the participation.”

Belfast Telegraph