One of Japan's largest brewers is targeting an unusual market sector with a campaign giving away cans of its new hit beer - mothers who have just given birth.

Kirin Brewery Co. is giving away a can of its product, named Free, to around 10,000 women who check out of around 80 maternity clinics in the cities of Tokyo and Osaka.

The three-week campaign has not set off howls of protest, however, as Free has 0 percent alcohol and the company says it is aiming to win over new mothers who like a drink but would otherwise feel unable to have a beer because of the effect it might have on their newborn child.

"Until recently there were no beers available that really had zero alcohol in them and new mothers, people who had to drive and people who do sports, for example, felt they were not able to have a drink," Haruka Higashimuki, a spokeswoman for Kirin Brewery, told Relaxnews.

"Our research showed that they often really did want a drink and to relax or reduce stress, but they couldn't," she said.

When Free was first released in April last year, demand was initially expected to be modest, with Kirin anticipating annual sales of 630,000 cases of the new beer, each case containing the equivalent of 20 633-mililiter bottles. That estimate was quickly raised to 2.5 million cases and then to 3.5 million cases. The final figure for the year eventually topped the 4 million cases mark.

The brewer even had to run full-page adverts in national newspapers apologizing to consumers for shortages of the drink due to its popularity.

As well as being alcohol-free, the beer is also cheaper than regular beer, with a 350-mililiter can of Kirin Free costing about Y150 (€1.14), while a regular beer around Y220 (€1.68) for a can of the same size.

Kirin's competitors among the "Big Four" brewers here have been quick to follow up with their own products. Asahi Breweries was the first to come up with a rival, unveiling its Point Zero on September 1. Before the month was out, Suntory Holdings had released Fine Zero and Sapporo Breweries started shipping Super Clear.