You can't blame immigrants for this trend. Many white/nonwhite women, as well as educated and career-driven women in general, are choosing not to have children, prioritizing their careers and personal goals instead.
First-generation immigrant women often hold traditional views, valuing marriage and motherhood. However, their daughters, the second-generation immigrants, tend to adopt the same mindset as native-born women, opting not to have children or having fewer children.
The decision by women, whether native European or second- and third-generation immigrants, to forgo having children is unrelated to immigration. Even without immigration, the preference of many European women to prioritize careers over motherhood would create a population decline, necessitating immigration to fill workforce gaps.
This shift isn't unique to Europe. Globally, in other countries in Asia and Africa, when women are empowered with education and opportunities, they often move away from traditional roles of marriage and motherhood, focusing instead on successful careers, entrepreneurship, or other ambitions.
Immigration isn't the cause of this mentality and as a woman, I think we can't force women to have children just for the sake of keep the population going! If a woman prefers to have a career over having a child, let her be...it's her life, it's her choice!