By Nancy Folbre
Americans passionately disagree about both the biology and the morality of contraception. Even many who skillfully practice what Thomas Robert Malthus termed the “improper arts” consider it a personal and, ideally, completely private choice.

But private choices are constrained by public policies. Both behavioral economics and recent empirical research help explain why access to long-acting, reliable, safe and reversible methods of contraception should be considered a public health priority.

Recent news coverage shows a pathological level of misinformation in some quarters, embodied in the assertion by Representative Todd Akin, the Republican Senate nominee in Missouri, that “legitimate” rape victims could never become pregnant against their will. On a more amusing note, a group of Catholic nuns in Ohio released a video contending that women who use contraceptives are less sexually attractive to men (feminist bloggers at Jezebel had a good time with this one).

Conservatives with an accurate grasp of biology are more likely to use a strategy of trivialization. The Republican speechwriter Peggy Noonan labels Sandra Fluke, Georgetown law student, as a “ninny” for suggesting that insurance coverage of contraception is a serious issue. Carrie Lukas, writing for National Review Online, derides the Democrats’ “cartoonish appeal to women to vote based on their ‘lady parts.’”

A more polite and perhaps more effective approach is simple avoidance. Ann Romney, asked whether she believed that employer-provided health insurance should be required to cover birth control, replied: “You’re asking me questions that are not about what this election is going to be about. This election is going to be about the economy and jobs.”

But unintended pregnancies – which account for about half of all pregnancies – have huge economic consequences for women’s employment, family welfare, public spending and children’s health. In a recent Guttmacher Institute study of women at 22 family planning clinics in 13 states, the most frequently cited reason given for using contraception was inability to take care of a baby at the time.

The Guttmacher Institute estimates that unintended pregnancy costs American taxpayers roughly $11 billion each year.

A report by Adam Thomas published in March by the Brookings Institution shows that unintended pregnancies are disproportionately concentrated among women who are unmarried, teenage and poor. It also summarizes evidence that these pregnancies set in motion a series of unfortunate outcomes that effectively reproduce poverty.

Conventional economic theory, still taught in many college classrooms, assumes that individual decisions reflect rational choices. From this perspective, a woman who engages in sexual intercourse without making the effort required to make low-cost methods of contraception succeed (which typically includes finding a partner willing to cooperate, as with use of a condom) must either be unpardonably ignorant or trying to get pregnant.

Behavioral economics, on the other hand, emphasizes that people often lack self-control, particularly when affected by “visceral factors,” such as hunger, thirst and sexual desire.

From this perspective, people need to protect themselves, pre-emptively, from carelessness that can lead to costly consequences. Even small differences in the form protection takes can have significant long-run effects.

Women sometimes forget to take birth control pills or let their prescription lapse. Partly for this reason, the American College of Obstetricians and Gynecologists now prioritizes use of IUDs and hormonal implants. Unpopular among older physicians and older women because they were once considered risky, these methods are now rated quite safe.

Mounting evidence suggests that making these new contraceptive technologies more economically accessible reduces abortions and unwanted births.

recent study in St. Louis enrolled more than 9,000 adolescent and adult women at risk of unintended pregnancy into a study that provided contraceptive counseling and offered participants the reversible contraceptive method of their choice at no cost; 75 percent chose either IUDs or implants.

The researchers reported a clinically and statistically significant reduction in abortion rates, repeat abortions and teenage birth rates.

Teenage pregnancies in the study group amounted to 6.3 per 1,000, compared with 34 per 1,000 on the national level. Abortion rates in the St. Louis area rose to 13.4 per 1000 women in 2010; in the study group, they amounted to 5.9 per 1,000.

The results corroborate earlier estimates of the payoff to public investments in family planning.

Republicans typically embrace cost-benefit analysis. But they seem reluctant to accept its application to the impact of contraceptive access on public health. Indeed, they have sought to cut funds for existing programs on the federal and state levels.

Apparently, they’re not such rational actors themselves. Maybe they’re just responding to something in their gut – in other words, their viscera.