Only Children by Choice vs. Only Children by Circumstances: Why Do Some Women Have Only One Child?

In an attempt to stimulate further theory and research on only children, we introduce two conceptual distinctions: Only children as independent variables vs. only children as dependent variables; and only children by choice vs. only children by circumstances. What little scientific research exists on only children to date focuses almost exclusively on only children as independent variables and fails to make a distinction between only children by choice and only children by circumstances. A focus on only children by choice as dependent variables explores the question of why some women choose to have only one child. As an empirical illustration, analyses of prospectively longitudinal data with a nationally representative sample in the United Kingdom (National Child Development Study) show that women who experience pregnancy complications are significantly less likely to have another child and significantly more likely to have only one child. Our results suggest that increased chances of pregnancy complications that American women now experience alone can explain about 10% of the increase in the number of only children in the United States in the last half century. If certain genes incline women to have pregnancy complications, it is possible that only children by circumstances are genetically more similar to children with siblings than to only children by choice.