The relationship between earnings and first birth probability among Norwegian men and women 1994-2008

I analyze whether the correlation between yearly earnings and the first birth probabilities changed in the period 1994-2008 in Norway, applying discrete-time hazard regressions to highly accurate data from population registers. The results show that the correlation between earnings and fertility has become more positive over time for women but is virtually unchanged for men – rendering the correlation fairly similar across sex at the end of the period. Though the (potential) opportunity cost of fathering increases, there is no evidence of a weaker correlation between earnings and first birth probability for men. I suggest that decreasing opportunity costs of motherhood as well as strategic timing of fertility to reduce wage penalties of motherhood are both plausible explanations of the increasingly positive correlation among women.