Unintended pregnancies cost American taxpayers $21 billion each year, according to a new analysis released by the Guttmacher Institute. That averages out to a cost of about $366 per every woman of childbearing age in the U.S. Overall, more than half of U.S. pregnancies are unintended, and roughly 1-in-20 American women of reproductive age have an unplanned pregnancy each year.

Nationally there were 1.5 million unplanned births in 2010. Public insurance programs like Medicaid paid for 68 percent of those births. "On average, a publicly funded birth cost $12,770 in prenatal care, labor and delivery, postpartum care and the first 12 months of infant care; care for months 13–60 cost, on average, another $7,947, for a total cost per birth of $20,716," the study found.

Both the rate and cost of unplanned birth vary considerably by state. As a percent of all births, unplanned births ranged from 31.8 percent in New Hampshire to 56.8 percent in Mississippi. Overall, states in New England and on the West coast had the lowest rates of unplanned birth, while Southern states had the highest.

In some states -- Georgia, Mississippi and Oklahoma -- more than 80 percent of unplanned births were paid for by public dollars. Georgia taxpayers spent nearly $1 billion on unplanned births in 2010, as did taxpayers in Illinois. California spent $1.8 billion, while unplanned births cost the state of Texas nearly $3 billion dollars in 2010.

If these numbers seem high, they could be a lot higher. Current investments in family planning services, like contraception, family visits and STD testing, save taxpayers $15.8 billion and prevent 760,000 abortions each year, according to a 2014 analysis in the Milbank Quarterly. Guttmacher estimates that expanding these services further could cut the cost of unintended pregnancies by an additional $15 billion.