We are American women with careers long devoted to women’s health who have been watching this election for many months, and we are not easily fooled.

Mitt Romney has asked us to give him a second chance. He now blithely asks us to forget his past pledges to “get rid of” Planned Parenthood, to eliminate Title X, the federal program that subsidizes contraceptive care for millions of low-income American women, and to overturn the Affordable Care Act, which promises historic increases in access to contraception and other critical preventive women’s health services. He now says all women deserve access to family planning, just not to have the government cover the costs, conveniently ignoring that who pays is precisely what this controversy is all about.

To us, federal funding for women’s health and especially for family planning is an issue of such importance that it alone should determine our votes. The choice is plain.  One candidate offers to build on the historic achievement of the Affordable Care Act in providing access to health care, with its many special provisions to preserve and advance the health and rights of women. The other vows to undo those gains on day one and reverse decades of progress.

A breakthrough clinical study of a large cohort of women in Missouri demonstrates just how high the stakes are and why the matter is critical not just to women but to the country as a whole. Released several weeks ago in the journal Obstetrics & Gynecology, the study shows conclusively that if Americans are serious about reducing unintended pregnancy and abortion, we must be willing to provide a range of  contraceptive choices to women at no or low cost. There has simply never been more compelling evidence that providing free contraception leads to positive outcomes and not to riskier sexual behaviors, as all-too-familiar conservative canards would have us believe.

The Contraceptive CHOICE Project, directed by researchers at Washington University in St. Louis, enrolled about 10,000 women ages 14 to 45 (with a mean age of 25) identified as being at risk of unintended pregnancy and desiring contraception. Each was given the reversible contraceptive method of her choice, at no cost, for two or three years.

The results are nothing short of remarkable. Contraceptive efficacy among participants increased significantly, and abortion rates fell to less than half the regional and national rates, even though the study participants were poorer, less educated, and therefore considered at greater risk than the overall population. The impact on the rate of births among teens was the most pronounced, with pregnancies falling dramatically to a rate of only 6.3 per 1,000, compared to a national average of 34.3 per 1,000.

The study contains a second dramatic finding. A majority of American women overall today use birth control pills or condoms for contraception—both low-cost methods but ones with a high rate of user error or failure. Most women in the CHOICE study, however, opted for longer acting and more reliable methods when cost was not a factor—75 percent selected an IUD or hormonal implant, and the greater efficacy of these methods is what accounts for the dramatic gains in the success rate across the group.

These are simply stunning outcomes. The study estimates that universal provision of contraception and the promotion of more effective contraceptive methods would result in fewer unintended pregnancies and would lower the number of abortions across the country by 62 to 75 percent every year.

That’s why the matter is so important to how we vote. Who pays for these services, and whether a trusted provider like Planned Parenthood is available to provide them, is exactly what’s at stake in this year’s election.

Unplanned pregnancies disrupt the lives of individual women and their families and levy a significant public health, economic, and social toll. No issue has done more to poison our nation’s politics. Despite a nearly universal desire for contraception, almost half of all U.S. pregnancies, totaling some 2 million each year, remain unintended or mistimed, and 43 percent of those pregnancies end in abortion. The estimated cost to taxpayers is $11 billion a year.

According to the Kaiser Family Foundation, the ACA has already expanded contraceptive coverage to more than 1 million young women who are now covered by their parents’ insurance through the age of 26. By 2016, approximately 13 million more uninsured women will be covered for contraception, including the IUD, hormonal implants, and injections that have been shown to be so much more effective.

New coverage will also provide other valuable and cost-effective care: at least one annual “well woman” visit to a primary care physician, access to emergency contraception (better known as the morning after pill), HPV testing, screenings for sexually transmitted diseases, and screenings for gestational diabetes, currently reaching epidemic proportions. And when a woman chooses to become pregnant, it will cover maternal health care, including breastfeeding support. The additional coverage for contraception alone will lead to nearly $3 billion in savings over five years, according to a study by the Oregon Health & Science University.

Simply put, the services guaranteed to women under the ACA represent the most significant advances in women’s reproductive health care since birth control pioneer Margaret Sanger went to jail for opening America’s first birth control clinic nearly a century ago, igniting a revolution that has inarguably changed the world. This historic event occurred on October 12, 1916. Ironically, this was 96 years ago to the day that Planned Parenthood became an issue of great contention in the second presidential debate.

Sadly, the controversies over women’s reproductive rights still live on. But one thing has surely changed: Today, American women have the right to vote. Exercising our suffrage to advance family planning will constitute our most powerful protest, one that may well determine the election’s outcome.

 Ellen Chesler and Andrea Flynn are fellows of the Roosevelt Institute and longtime women’s women’s health analysts and advocates. Chesler is the author of Woman of Valor: Margaret Sanger and the Birth Control Movement in America.

Photo credit: AP/Pablo Martinez Monsivais