The United States is the only country in the developed world, and one of just two countries on the planet (it's joined by Papua New Guinea), that doesn't guarantee paid time off for new mothers.

This is not only embarrassing and unethical, it's counterintuitive and detrimental to the nation's economic well-being. It's long past time for there to be federally mandated paid maternity leave in the US.

If we really cared about American mothers, as we claim to on Mother's Day, we would promote laws that help protect their health and livelihood.

Women make up 47 percent of the workforce in America. Moreover, in 40 percent of American households, women are the primary breadwinners.

Simply put, women are not only an essential part of the US labor force, families across the country are depending on them.

Yet, 88 percent of working women in the US do not have access to paid maternity leave. What's more, around a quarter of working women return to work within two weeks after giving birth because they can't afford to lose their jobs and they're not given paid leave.

This is completely unfair and irrational, and it has reverberating consequences.

Paid maternity leave is common sense, and it's good for the economy.

According to research from University of Massachusetts sociologist Michelle Budig, a woman's earnings decrease by 4 percent for every child she has, yet a man's earnings increase by 6 percent for every child he has.

In other words, the lack of paid maternity leave also contributes to the perpetuation of the gender pay gap in the US -- we've essentially turned motherhood into a punishment in this country.

Research shows women are far more likely than men to take a significant amount of time off work, reduce the amount of time they work, turn down a promotion or even quit their jobs in order to care for their families.

Correspondingly, evidence points to the fact women are far more likely to stay in the labor force if guaranteed paid leave, which also helps stabilize their wages in the long run. This also translates into fewer costs for businesses in terms of turnover and training.

Paid maternity leave means healthier babies and mothers.

Beyond economics, paid maternity leave has a number of massive benefits in terms of health.

A 2011 study of 141 countries with paid leave policies, for example, showed paid parental leave can help reduce infant mortality rates by 10 percent. Research also shows paid maternity leave leads to a higher likelihood babies will get properly vaccinated.

Additionally, a study by researchers at the Centers for Disease Control and Prevention (CDC) showed working women who received at least 12 weeks of paid maternity leave had a higher probability of breastfeeding their babies and continuing to do so for at least six months.

According to the CDC, babies who are breastfed are less likely to get numerous infections as well as asthma, sudden infant death syndrome (SIDS), diabetes and obesity.

There is also widespread evidence paid maternity is good for mental health. One study, for example, showed women who took more than 12 weeks of paid maternity leave were less likely to report symptoms of depression.

There's no denying paid maternity leave is good for the economic, physical and mental wellbeing of mothers, and it's time for the US to acknowledge and embrace the facts.

The US has a lot of room for improvement in multiple respects when it comes paid leave (like guaranteed paid vacation), but standing behind American mothers, and ensuring they're in a position to succeed and stay healthy, would certainly be a good start.