The role of involuntary factors in explaining the gap between desired and realized fertility in developed countries

Daniel Devolder, Universitat Autònoma de Barcelona

Desired family size in low fertility countries is generally higher than the Total Fertility Rate, even after accounting for tempo changes that bias the period fertility levels downward. We use Bongaarts' model to analyze the role of involuntary factors in the explanation of this gap. Two kinds of factors will be studied. On one hand biological factors (sterility, low fecundability, risk of miscarriage, etc.) may explain why a proportion of women who want children will remain childless. On another hand social factors associated with the timing of family formation and separation, may also explain why final fertility levels are lower than desired one. We will use data from FFS surveys and a microsimulation model in order to estimate the role of these involuntary factors in the explanation of the gap between observed and desired fertility levels.