Does the month of birth influence the timing of life course decisions? Evidence from a natural experiment in Italy

Social scientists have for a long time observed a strong negative relationship between time spent in education and the timing of family formation. However, individual unobserved characteristics influence the two processes simultaneously: ignoring these characteristics means overestimating the effect exit from education has on union formation and first birth. Using data from the I.D.E.A. (Inizio dell’Età Adulta) survey (2003), which provides information on Italians aged 23-28 and 33-38, I employ a birth-month experiment on a sample of 3,000 young adults in order to explore whether a different month of birth leads to regular and relevant differences in life course decisions among young Italians. I investigate the timing of marriage and fertility as a function of educational attainment in Italy that leads to exogenous variation in the age of school completion. The results suggest that women born in the last month of the year are less likely to have lower secondary schooling as their highest educational attainment, and they are more likely to have achieved more advanced education. This result influences the timing of first marriage and subsequently the timing of first birth. The analysis suggests that social age, as determined by the school cohort, rather than biological age, is an important determinant of the timing of demographic events during the transition to adulthood.