The Register Office for Scotland said longer life expectancy and better medical care seemed to be extending a downward trend in the mortality rate.

Just 12,770 deaths were recorded in the first quarter of this year, compared to 13,493 for the same period in 2008 -- a fall of 5%.

Registrar General for Scotland Duncan Macniven described the new figures as “memorable”. He said: “Death rates fluctuate, and we shouldn’t make too much of a single quarter, but we’ve seen a reduction in the last two quarters, giving the lowest number of deaths and lowest death rate in the first half of a year for at least three decades.”

The lower figures are part of a long-term downward trend, the Register Office said, and go some way to explaining why Scotland’s flagging population levels are finally beginning to revive after years of gradual decline.

Other factors include net immigration to Scotland, although the latest survey did not take these numbers into account.

Some of the more common causes of death appear to be becoming less prevalent across the country, bucking the image of the unhealthy Scot who drinks too much and overeats fatty foods.

Chronic liver conditions accounted for only 223 deaths between April and June 2009, down significantly from rates of between 269 and 283 in the equivalent period of each of the last three years.

Deaths from stroke and coronary heart disease fell by 6.5% and 10.7% respectively, and deaths from cancer fell by 0.6%.

Scotland’s biggest killer remains circulatory diseases, including heart attacks, which account for nearly one third of total deaths. Cancer is the second most common cause of death.

Among fatal conditions becoming more frequent, there was a sharp rise in deaths categorised as “ill-defined and unknown causes”. Though the numbers under this heading remain relatively low compared to the overall population, last year’s rate more than tripled from 30 to 135. In each of the last three years, the number has remained between 30 and 34.

The vast majority of Scots die in old age, as may be expected, but the level of infant deaths was also down last quarter by around one fifth from its long-term average.

The total number of births, however, was down very slightly from last year’s figures. New babies swelled Scotland’s population by 14,866 between April and June, just nine fewer than the same period in 2008 but nearly 600 more than the equivalent quarter in 2007.

Marriage levels were also down by a tiny fraction, falling from 7904 to 7872, but civil partnerships were up considerably from last year.

Nearly 150 same-sex couples tied the knot over the quarter, a rise of 31 from last year’s level. More female couples were registered than males, with women accounting for 83 partnerships and men 62.

In another sign that society may be becoming more permissive and moving away from traditional ideas of family, the number of babies born to unmarried couples has also continued to increase.

During the year to date, more than half of all newborns had unmarried parents, continuing a trend first set in 2008. The proportion of babies born to unmarried couples has risen steadily in recent decades, increasing by about a quarter in the last 10 years. In 1999, only 41.2% of children arrived out of wedlock.

Deaths coronary heart disease fell by 10.7%