Mothers With First-Born Girls Work More

A study released in April 2011 by economists Andrea Ichino, Elly-Ann Lindström, and Eliana Viviano delivered a puzzle: in the United States, the United Kingdom, Italy, and Sweden, women whose first child was a boy worked fewer hours — and were less likely to work in a typical week — than women whose first child was a girl.

The paper, "Hidden Consequences of a First-Born Boy for Mothers" (IZA Discussion Paper 5649, later published in Economics Letters), found the pattern across four very different economies. The sex of a first child is essentially random — so why would it move mothers' labor supply at all?

The researchers' answer was fertility, not parenting style. Following earlier work by Dahl and Moretti, they showed that a first-born boy increases the probability that a marriage survives. In these advanced economies, that greater marital stability led women to have more children — and more children meant less paid work. The fertility effect of stable marriages more than offset the effect economists had expected (that fewer pregnancies would be needed to get a boy in countries with son preference).

The finding was a useful reminder that the relationship between children and maternal labor supply runs through indirect channels — marriage stability, fertility decisions, household bargaining — that are invisible if you only count the number of children and their ages.

The study's four countries (the US, UK, Italy, Sweden) are not India, and nobody has replicated the result in a developing-country context where son preference operates very differently. But as a demonstration of how a random variable — a child's sex — can ripple through marriage, fertility, and work, it remains one of the more elegant natural experiments in family economics.

Reporting: The Wall Street Journal, Real Time Economics; paper: Ichino, Lindström & Viviano, IZA DP 5649 (April 2011).