Does the combination of spouses’ birth orders influence their divorce risk?

Vegard Skirbekk, International Institute for Applied Systems Analysis (IIASA)
Torkild Lyngstad, Statistics Norway

Marriages of couples with identical birth orders have been suggested to run higher risks of divorce than marriages of couples with different birth orders. Others have rejected the idea that birth order should have any effect on divorce risk. No empirical study has so far provided a reliable investigation into birth order effects on divorce rates. This study will fill this gap in the literature. Discrete-time hazard regression models are estimated on a register-based longitudinal data set covering all Norwegian first marriages contracted between 1980 and 2000. The huge volume of the data facilitates estimating parameters for many combinations of spouses’ birth orders. Our results indicate that marriages where both husband and wife are single children are the most stable, while marriages to two first-borns run the highest risk of divorce.