This article considers the estimation of the causal effect of fertility on female-labor-force participation equations. My main concern is to examine two considerations, the endogeneity of fertility and the
impact of controllingf or unobservedh eterogeneitya ndThis article considers the estimation of the causal effect of fertility on female-labor-force participation equations. My main concern is to examine two considerations, the endogeneity of fertility and the
impact of controllingf or unobservedh eterogeneitya nd for predeterminede xisting children.U sing PSID data, a switching binary panel-data model that accounts for selectivity bias as well as for other forms
of time-invariantu nobservedh eterogeneityi s estimated. Individuale ffects are allowed to be correlated with the explanatory variables, which can be predetermined as opposed to strictly exogenous. Family
sex composition is used as an instrument for exogenous fertility movements. The results indicate that
exogeneity assumptions of children variables induce a downward bias in absolute value in the estimated
negative effect of fertility on participation, although the failure to account for unobserved heterogeneity
overstates this effect. Moreover, stronger effects of fertility are found when existing children are treated as predeterminedb ut not strictly exogenous variables.[+][-]