When it comes to paid maternity leave, the United States is in the postpartum dark ages.

One hundred and seventy-seven nations -- including Djibouti, Haiti and Afghanistan -- have laws on the books requiring that all women, and in some cases men, receive both income and job-protected time off after the birth of a child. But here, the Family and Medical Leave Act of 1993 provides only unpaid leave, and most working mothers don't get to stay home with their newborns for the 12 weeks allowed by the law. Many aren't covered by the FMLA; others can't afford to take unpaid time off. Some go back to work a few weeks after giving birth, and some go back after mere days.

The century-long battle for maternity leave in America is a story of missed opportunities and historical accidents, further slowed by activists' miscalculations and some well-funded opposition. In other words: It didn't have to be this way.

As far back as 1919, when the Model T was switching from a crank to an electric starter, the U.S. government came close to signing on to an International Labor Organization agreement, supported by 33 countries, that said women workers should receive cash benefits in addition to job-protected leave for 12 weeks in the period surrounding childbirth. That same year, Julia Lathrop, the chief of the Labor Department's children's bureau, issued a report on international maternity leave policy in which she decried the United States as "one of the few great countries which as yet have no system of State or national assistance in maternity." She had recently returned from Europe, where Germany and France had paid-leave laws that had been in place for decades.

But this first real drive for maternity leave fell victim to petty infighting. Though many members of a key labor group wanted to include "maternity insurance" in its recommendations to Congress and President Woodrow Wilson, it was omitted after an internal dispute over who would be covered. Other early proponents of maternity benefits got tripped up by whether to insist that protections and income for pregnant women be part of national health coverage (which, sadly, they seemed to think was around the corner).

At other times, history has intervened. When women flooded the workforce during World War II, the Labor Department's women's bureau recommended that women get six weeks of prenatal leave, as well as two months following childbirth. Then, just as pressure for change was mounting, the war ended, men returned home to reclaim their jobs, and the drive fizzled.

Politics have posed an even bigger obstacle. The debate over maternity leave has long served as a proxy for tensions surrounding the presence of women in the workplace. Remember that, until 1978, it was legal in most states to fire women for becoming pregnant; some conservatives defended the practice as a way to encourage women to return to the home.

But even some feminists objected to giving women job-protected time off around birth, because they felt that their gains were too precarious, and their determination to ascend from the pit of sex discrimination was too great, to risk drawing further attention to maternity. In the early 1970s, some women challenged school board policies requiring pregnant teachers to take maternity leave for several months before and after birth. So it wasn't entirely surprising that, when Rep. Howard Berman (D-Calif.) spearheaded a national proposal for leave in 1984, it encountered the same resistance.

"Influential feminist activists in Washington opposed maternity leave because it wasn't treating women the same as men," says Joan Williams, director of the Center for WorkLife Law at the University of California at Hastings. "They said: 'No, no, no. We don't want national maternity leave. We want to fold maternity into other medical needs.' "

And that is what ultimately happened. During the decade or so when advocates pushed for what would become the Family and Medical Leave Act, their working definition of what leave should include shifted. At first, it applied only to mothers, then to new parents and later to all workers who need to care for family members. This change was good in that it allowed fathers to be more involved and helped broaden political support for leave legislation -- but it came at a price: The prospect of so many would-be leave-takers made business interests more aggressive than ever in their efforts to make sure that the time off wouldn't be paid.

"In Europe, it's parental leave," says Steven Wisensale, a professor of public policy at the University of Connecticut and the author of "Family Leave Policy: The Political Economy of Work and Family in America." "When you get into family leave and you're suddenly concerned about caring for elderly people, it becomes a little more nebulous."

And so, after years of debate, during which Sen. Bob Dole (R-Kan.) filibustered and President George H.W. Bush twice vetoed family leave legislation, the law President Bill Clinton finally signed in 1993 was so shrunken from its original form that it was barely recognizable.

Earlier versions would have given all workers 26 weeks for medical leave and 18 for parental leave. But in its anemic final form, the Family and Medical Leave Act grants only 12 weeks off and covers only a little more than half of workers, leaving out those who work for companies with fewer than 50 employees or who have logged less than 1,250 hours in the past year. And because the leave is unpaid, many of those who are covered can't afford to take the time off.

The impact of our national policy is brutal. According to research by economists Sara Markowitz and Pinka Chatterji and published in 2008 by the National Bureau of Economic Research, women who return to work soon after the birth of a child are more likely to get depressed than other mothers. They're also less healthy: According to the study, longer maternity leaves are associated with improvements in mothers' overall health.

And, not surprisingly, the lack of time together hurts mothers' relationships with their infants. Mothers who went back to work before the six-month mark were less likely to tickle, play with or cuddle their infants than those who returned between six and nine months after giving birth, according to a 2006 nationwide study by Child Trends, a research group.

The effect of all this on babies can be serious and lasting: In an article published in the The Economic Journal in 2005, researchers found that infants whose mothers had 12 weeks of maternity leave or fewer had lower cognitive test scores and higher rates of behavior problems at age four than children whose mothers had longer leaves. In Europe, longer paid maternity leaves are linked to lower infant and child mortality.

But as inadequate as the FMLA is, its passage offers useful lessons. Liberals who spearheaded the effort managed to make common case with some conservatives concerned about "values" issues. For example, they won over Henry Hyde, then a Republican congressman from Illinois who opposed maternity leave, by convincing him that job-protected time off from work would help bring down the abortion rate.

If a new drive for paid leave is to gain traction, similar alliances will be key. Support is strong across the ideological spectrum, should anyone try to span it. According to a survey of more than 3,400 adults conducted by the Rockefeller Foundation and Time in September, 62 percent of Republicans and 74 percent of evangelical Christians believe that businesses should be "required to provide paid family and medical leave for every worker who needs it." With support even higher among Democrats, it's hard to think of another issue that unites so many voters but remains so perennially neglected.

Another challenge will be to explain to businesses that they aren't expected to bear the financial burden. In California and New Jersey, the states that already provide paid family leave, benefits -- in both cases, up to six weeks off, partially paid, for workers to care for either a sick family member or a new baby -- are funded entirely by employee contributions through an extension of the states' temporary disability insurance plans.

Finally, states probably need to pass paid leave laws before such legislation can succeed nationally. Unpaid leave followed this pattern; at least 34 states had enacted unpaid family leave laws by the time the FMLA was signed. Auspiciously, the Obama administration's budget for next year includes $50 million for a State Paid Leave Fund that would help launch state programs.

"This money is really important. Already, about half of the states are doing something to move toward paid leave -- holding hearings or introducing legislation," says Debra Ness, president of the National Partnership for Women and Families. "This could be the push that would enable them to take that next step."

With that next step as a start, maybe we could have a national paid leave law by, say, 2019 -- only a century after we missed our first opportunity.