The United States is only one of two nations in the developed world that doesn't offer paid maternity leaveas a matter of national policy.

In recent years, outcry over that fact has led to a renewed push for the U.S. to develop a modern maternity leave policy—one that reflects the fact that nearly three-quarters American mothers serve as breadwinners. (Read more at 'Moms Rising.')

That lack of financial support for new mothers has been blamed for everything from a high 'drop-out' rate of female workers, to lower breastfeeding rates, to decreased rates of vaccinations for babies of mothers who go back to work early.

But a new report titled 'When Family Friend Policies Backfire' from Claire Cain Miller of The New York Times analyzes the results of several new studies on global maternity leave and flex work programs, and suggests that the United States might want to understand how to optimize any programs that it develops, in order to prevent some discriminatory effects of new policy.

Among the article's findings:

-"In Chile, a law requires employers to provide working mothers with child care. One result? Women are paid less."
-"In Spain, a policy to give parents of young children the right to work part-time has led to a decline in full-time, stable jobs available to all women — even those who are not mothers."
'"Elsewhere in Europe, generous maternity leaves have meant that women are much less likely than men to become managers or achieve other high-powered positions at work."

Miller points out that after countries implemented mother-friendly, flexible policies, many women found their careers and incomes stalled by employers who —consciously or not —punish them for those accommodations. Part of the problem, Miller suggests, is when the employer, rather than the state, is expected to bear the cost of maternity leave and flex work, employers will discriminate against employees in hiring or promotion in order to avoid bearing additional costs.

To some women, more flexible work is worth the price of decreased pay or opportunities to promote. But for others, workplace equality for women means that the government and employers must accommodate the biological reality of pregnancy and childbirth for women. Miller's report on how other nations are faring is a worthy read in the ongoing debate.