The fertility behavior, in its motivations, decision - making process, and the associated attitudes, can be considered a social behavior which takes place in a social context. Migration removes the migrants from a social, cultural, and economic context and sets them in a new one. If
these two contexts are not similar, the migrants may be expected to
behave in a different manner at the destination, compared with the place of origin. Therefore, some research questions such as the following may be posed:
- To what extent and by what mechanisms can the changes in residence
lead to the changes in human behavior; in relation to the fertility and reproduction?
In order to answer these questions scientifically, some researchers
have tried to establish the links between the fertility and migration through using a range of various research hypotheses. Four major hypotheses have been put forward, they are: migration disruption; adaptation; migrant selectivity; minority group status. The moving itself may lower the fertility rate through delaying marriage, dividing the
spouses, or reducing the desire for an immediate pregnancy. Migrants may be considered as a self - selected group that they would have had a
lower or higher fertility rate, compared with their non - migrant counterparts at the place of origin, if they had not migrated. The adaptation hypothesis poses that as migrants adapt to the society of destination, their fertility levels and patterns converge to those of the native - borns as well. The minority group status hypothesis considers the characteristics of the minority groups which are different from the majority ones at destination. According to this hypothesis, the socio economic variables related to the fertility are not the same, within
various racial and ethnic groups.
Thus, each of these four major hypotheses may have a significant
role to play in describing the relationship between migration and the
fertility. Of course, the strengths and weaknesses of any hypothesis depend largely on the circumstances in which it is applied. The selection of an appropriate theoretical framework depends on the nature of one"s study, its objectives, target population, and the data available.