For the German case, the relationship between international migration and population development can be observed in the number of children born to foreign citizen mothers, which has strongly increased since the 1960s (112,358 births in 2011). These mothers are responsible for 17 percent of all births in Germany, although non-citizens only constitute 7.8 percent of the German population. There are several causes for the growing proportion of these births of non-citizen mothers. First, the number of non-citizen residents has increased with the rising number of migrants in the last decades, thereby bringing more potential mothers (compare Interner Link: chart 2). Second, migrants usually migrate while they are young. The average age of the non-citizen population in 2011 was 39.4 years of age, while the average age of the German population was 44.4 years of age. This also leads to a relatively high number of potential mothers. Finally, women without German citizenship give birth to a higher average number of children than do women with German citizenship. Thus past migration and the resulting births have generally helped make the otherwise aging German population younger.
Processes of Adaptation
However, a comparison of the total fertility rates suggests that in the course of integration processes, the fertility of non-citizen women in Germany draws nearer to that of German women. In 1990 the average fertility of women with foreign citizenship was 2.04 children, compared to 1.26 children for German women (see Chart 5). By 2011, this difference had decreased significantly: the average number of births of non-citizen mothers was 1.58, as opposed to 1.33 births for women with a German passport. The higher birth rates among migrants are usually attributed to the higher average number of births in their countries of origin. It is assumed that the longer they live in Germany, the more they adapt their family planning and fertility level to fit the ideals and conditions of the host country. However, for newly immigrating women one should consider that also in most countries of origin the total fertility rate has dropped considerably.