Germany's aging population and a birthrate below the replacement rate of 2.1 children per women has prompted concerns over the declining population's impact on the economy and social security.

To fill the gap, Germany has relied on importing workers and accepting migrants, including more than 800,000 asylum seekers who arrived in the country in 2015.

The statistics released on Monday show German women had 1.43 children on average in 2015, up slightly from 1.42 in 2014.

However, the birthrate non-German origin women increased from 1.86 to 1.95 children per woman from 2014 to 2015, thereby "contributing significantly to the increase in the combined birthrate of all women," the statistics office said.