The factors that explain why women live alone at advanced ages are diverse: the economic situation, state of health, place where they live, educational level, whether they are foreign or not, whether they have a partner, whether they have children, etc. Even though all of these can influence to a certain extent the probability of women living alone at advanced ages, the most relevant factor is whether or not they have had children. Specifically, among the elderly women who have not had children, in 2011 some 38.3% lived alone, while among those that had had children, the sum was considerably lower, standing at 26.4%. This difference between those that have had children and those that have not had them is considerable. But not only is it important whether or not they have had children; how many children they have had also matters. As we could imagine, the probability of living alone at an advanced age is lower the higher the number of children.

The clear relationship that we observe between the fact that they live alone at advanced ages and their fertility history is a strong association and a significant one in statistical terms. In other words, it is a relationship that is maintained even in more sophisticated analyses that simultaneously take into account demographic and social characteristics that may also bear an influence, such as age (it is not the same to be 65 as to be 100 years old), educational level, place of residence, migratory status, home ownership or current civil status.
We could think that, in addition to the number of children, the civil status of elderly women is a very relevant factor for understanding this phenomenon. In fact, as it is easy to imagine, there are very few elderly women who are currently married and live alone (under 2%), whereas among widows the figure exceeds 50%. In other words, it is much more probable for an elderly woman to live alone if she is single or a widow than if she is married and her partner still alive, because in the latter case, the immense majority live with their husband and/or with other family members.
Even though the civil status is decisive, the number of children is still a relevant factor in explaining the probability of living alone at advanced ages. And the fact is that, independently of civil status, women with children have a lower probability of living alone at advanced ages in comparison with those who have never had children. For example, we know that in general terms, some 53% of widowed older women live alone, but within this group there are many more that live alone if they have not had children (66% of widows) by comparison with those who have had children (52%). And the same thing happens with other civil statuses. In other words, as much among single women as among married, separated, divorced or widowed women, it is more probable that they will live alone at advanced ages if they have not had children.
This regularity that we find between number of children and living arrangements at advanced ages is quite intuitive and easy to understand. The more children women have had, the more probable that they will live accompanied in their old age because, in general terms, large families establish more family bonds than small ones. It is important to bear in mind, however, that although the number of children is a very important factor in causing the probability of living alone to fall, it is not completely determinant to make this so. In fact, the data also permit an alternative reading: children tend to reduce the probability of living alone, but there are quite a lot of elderly women who, although they have had children, live alone (26.4%) and, to the contrary, there are many more that have not had children and live accompanied (61.7%).

We can consider, therefore, that in the phenomenon of living unaccompanied at advanced ages, there is a combination of elements that are related with individual decisions, but also with more structural impediments or restrictions. With the data from the census it is impossible to distinguish whether any particular behaviour (in this case, living alone) is voluntary or involuntary. Also, everything points to a certain simultaneity of factors: on the one hand, personal autonomy is an increasingly significant value, for elderly people too; on the other, the objective conditions are present to do so, because now elderly people have more social and economic resources to live alone than in the past.