Julius Ilciukas

I develop a new methodology to estimate how parenthood and its timing affect labor market outcomes, leveraging variation from intrauterine insemination (IUI). The method exploits quasi-experiments where individuals not initially assigned to treatment may undergo repeated assignments, as when failed IUI attempts lead to subsequent procedures. By leveraging entire assignment sequences, it separates treatment effects (parenthood versus childlessness) from timing effects (earlier versus later childbearing). Using Dutch administrative data, I find that motherhood persistently reduces earnings (10–28%) and work hours (10–22%), causing up to half of post-childbirth gender inequality. Delayed childbearing—even when unintended—mitigates women’s losses.

We estimate the impact of having siblings on the cognitive and non-cognitive development of first-born children. By exploiting quasi-experimental variation in the sequence of parents' in vitro fertilization (IVF) attempts for a second child, we identify effects for first-born children who would remain only children if all IVF attempts fail. Using Danish administrative registers linked to nationwide school surveys, we find that siblings have little effect on test performance (math and reading), personality traits (conscientiousness, agreeableness, emotional stability), or classroom and school well-being. Overall, we conclude that having siblings neither harms nor spurs the first-borns' cognitive and non-cognitive development.

I study how reduced retirement opportunities in one generation affect fertility in the subsequent generation. I use administrative Dutch data and exploit the 2006 Dutch pension reform, which induced individuals born from January 1, 1950 onward to delay retirement while exempting those born earlier. I find that this reform reduced fertility among women with affected mothers. The reduction is economically significant and persists after the impact on retirement fades out. I supplement my analysis with survey evidence and argue that the fertility reduction can be explained by reduced grandparental child care supply.