Maybe you've just moved in with your boyfriend. Maybe you've just started dating a guy who seems special. Maybe you've got a friends with benefits situation that seems to be working for now.

Then you miss your period, even though you're using birth control. An at-home pregnancy test proves what you suspected -- you're pregnant. You feel sick, and it's not just morning sickness.

Now what?

You're not sure if you want to keep the baby and you're not sure if you should even tell your lover.

If you did, what difference would it make, anyway? He has no say if you choose to have an abortion. But what if you want to have the baby -- either to raise or put up for adoption? Until the baby is born, the father-to-be has no responsibility to help you with any of the costs related to the pregnancy -- and there are plenty. Between maternity clothes, OB/GYN visits, ultrasounds, tests, nutritional supplements, birthing classes, perhaps even unpaid sick days from work or the loss of a prospective job because few employers want to hire an obviously pregnant woman -- it isn't cheap or easy to be knocked up.

That doesn't seem fair to Shari Motro, a professor of law at the University of Richmond, Virginia. That's why Motro has introduced the concept of preglimony.

"Why don't we recognize that when a woman gets pregnant with a man to whom she is not married, the pregnancy should be both parties' responsibility?" she writes in the Stanford Law Review. Not to say that some men don't help out; many do. But for those who don't "the law gives them a free pass. In short, until and unless paternity has been established, a pregnant woman and the man with whom she conceives are legal strangers."

Except they aren't really strangers; they've shared an intimate act. But they aren't spouses, either. They're something in between, either as tenuously connected as a no-strings-attached situation or a cohabiting couple. "When a man and a woman have nonreproductive sex, they knowingly engage in an act that has a reasonable possibility of radically interfering with the woman's life, and disproportionately so," she says. "Preglimony is a new word; it is not a new practice. It's time the law noticed."

Pregnancy is a big deal for a woman, no matter how it occurs, and according to the first state-level analysis of unintended pregnancies last year, at least 4 in 10 pregnancies were unwanted or mistimed. Given the many types of contraception available, there isn't much sympathy for whose who accidentally become pregnant. Still, she notes, no form of birth control is foolproof, and all types of contraception as well as abortion come at a great cost to women, especially women who are not financially independent. But the costs aren't just financial.

"Pregnancy changes everything from a woman's pulse to the chemicals that influence her thoughts and feelings. It can present her with unparalleled opportunities for personal growth, healing and joy and it can jeopardize her independence for years to come," Motro writes in "The Price of Pleasure." Women often make light of the burdens of pregnancy because "pregnancy-related impairments have and continue to deter employers from hiring women and focus on the risks of abortion may play into the hands of those who wish to re-criminalize it."

Acknowledging that, Motro would like to see some sort of relational default or what she calls preglimony, a "legal framework defining a man's duty to help support his pregnant lover," to address a growing issue -- some 41 percent of babies are born to unmarried women even though 40 percent of them are cohabiting.

Creating the structure for that is complicated, but in the meantime she believes we can support men who are willing to pay their fair share through tax laws, just like alimony. Currently, any financial help a man contributes toward his lover's pregnancy is considered a gift or child support, and thus offers him no tax benefits. Alimony payments do, however, and she argues preglimony should, too. Not only will it "reward and encourage men who are prepared to support their pregnant lovers," but it will lessen the need for shotgun marriages that often lead to divorce.

That's not to say it should embrace pregnancies resulting from nonconsensual sex, including sex in which a woman knowingly and deceitfully gets pregnant. Nor should it be required; she believes couples should be able to opt out.

Of course, asking men to share in the costs means that they will have more say about how a pregnancy should be handled, perhaps leading some to pressure a woman to have -- or not have -- an abortion. Still, that will ultimately be the woman's decision. And, she notes, "increasing support for pregnant women regardless of the pregnancy's outcome will, over time, change abortion from a form of birth control that lets men off the hook into something both parties are invested in preventing."

As long as people continue to have sex outside of marriage, and as long as many see marriage as obsolete and increasingly live together, we need to be talking about the price we play for pleasure.

"In life there are no guarantees. Men and women who do not want children have sex anyway despite the wild roll-of-the-dice that it entails. This is the fundamental risk at the heart of making love. This is the true price of pleasure, a price no law can erase," Motro says. "But the law can -- indeed it inevitably does -- set the baseline. It is up to us to decide where."

A version of this article appeared on Vicki Larson's personal blog, the OMG Chronicles.