Joya Misra, Michele Budig, and Irene Boeckmann from Sociology immediately wrote up a short summary of their detailed cross-national research on family policies showing how careful policy design, as well as changing cultural norms, contribute to positive outcomes for women’s employment and earnings. Marta Murray-Close from Economics pointed out that the relative size of effects matters: the benefits of a large long-term increase in women’s employment may well outweigh any short-term reductions in promotions for a handful of women at the upper reaches of corporate management.

Silke Staab, a research specialist at UN Women, offered some perspective on Miller’s discussion of Chilean policies, which led off her piece. Yet, requiring Chilean employers to provide child care for women have made it expensive for them to hire women. But that was partly the intent of the law, which was originally passed in 1917 when relatively few mothers were employed. Staab observes that today, in Chile, almost everyone agrees this policy is a really bad idea. (For more discussion see the new UN Women report on Progress of the World’s Women.

I focused my own attention on an unpublished paper by economist Mallika Thomas, which Miller summarized, purporting to show that passage of the Family and Medical Leave Act (FMLA) of 1993 in the U.S. increased women’s employment but reduced their likelihood of promotion by an even larger percentage. I found this claim startling, because the FMLA covers less than one half of U.S. workers, is not restricted to maternity leave, and, because it is unpaid, is not taken up by many of the workers who are covered. According to a Department of Labor report published in 2012, more than half of all leaves are taken for employees’ own illness. Yet Thomas describes her paper as a study of “mandated maternity benefits.”

Ploughing through an on-line version I found a really interesting—and, at first glance, sophisticated–model showing how the FMLA may have changed employers’ perceptions of women employees, making it harder for them to identify those with the strongest career commitments. This information problem, Thomas argues, led to more uncertain estimates of future labor supply, which in turn, made it riskier to promote any women at all. She has a point here: employers have an incentive to discriminate against women in promotions if their future effort on the job is harder to predict than that of men. But Thomas doesn’t seem to include any explicit consideration of the effects of the FMLA on turnover, and this seems like a pretty serious flaw.

The FMLA, like many of the corporate policies explicitly adopted by many firms for their professional and managerial employees, reduces job turnover by making it more likely that mothers will return to the job after their leave is over, rather than quitting to stay home with their baby for a few months and then seeking another job.

In this sense it reduces uncertainty. Indeed, the loss to a firm when an employee leaves the firm is almost certainly greater than the loss that might occur because the same employee takes the maximum twelve-week FMLA leave even if she also lowers her future work intensity somewhat as a result of ongoing family responsibilities. At the very least, turnover effects belong in any theoretical model of the effects of the FMLA. Reduced turnover is central to arguments that both unpaid and paid family leave can create benefits for both employers and employees (See, for instance, this recent Wall Street Journal article).

The empirical results that Thomas reports could result from the fact that the policy may increase heterogeneity among women employees, because more women stay on the job rather than quitting to take time out for family care. The average probability of promotion may be lower because the promotion pool now includes more women who, under the previous policy regime, would simply have dropped out.

I hope Thomas will respond to this point in her future work. I also hope that the New York Times will improve its reporting on these issues by consulting a broader spectrum of policy experts. David Leonhardt, managing editor of the Upshot, suggested back in 2010 that feminists had been lax on family policy. I challenged that view right away on the Economix blog.

Oops, maybe my efforts backfired. But somehow, I don’t think that’s the problem.