No matter what your position on the rights or wrongs of abortion, the Roe vs. Wade decision, made 40 years ago today, was one of the most momentous in American history. It has had profound personal, social, political and demographic effects.

Since 1973, more than 50 million abortions have been performed in the United States. More than 30 percent of all women have had an abortion. That last fact alone explains why a dispassionate discussion of this topic is difficult. We all carry intensely personal baggage on this issue. Even from my male perspective, that is true.

During my 33-year medical career, I have done abortions. More accurately, I have ended pregnancies in very rare instances when they posed a risk to the life of a mother. However, my intention has always been to preserve the life of a mother, never to end the life of an unborn child. I will never forget the anguish of those choices.

Yet abortion didn't trouble me in 1973. I went into medicine and OB/GYN partially because of my neighbor in Tucson, Ariz. He became the first Arizona physician willing to perform abortions when they became legal. As a premed college freshman, I wasn't bothered by the logic of Roe. I was certainly in the demographic that is (still) most likely to support abortion -- young men who would not mind having someone else make a little problem go away.

In 2013, some believe that the debate over abortion is over. You would think that the re-election of a president who unapologetically supports publicly funded abortion without restrictions ends the argument. Yet it rages on.

Why? Because the last 40 years have brought advances in medical care, as well as a surprising change of heart among the American people.

When I started medical school in 1976, babies born below 28 weeks were not resuscitated. They were not considered viable. Today, the lower limit of viability is 23 weeks. The incredible detail of ultrasound makes it difficult to ignore the obvious humanity of a life before birth. Intrauterine fetal treatment and surgery is an expanding option.

But when fetal status as a patient depends on the decisions of others, we have clear evidence of an unresolved moral tension.

Opinion polls have borne this out. Slate's William Saletan recently noted that liberal attitudes have increased on a range of issues -- with the exception of abortion. "When public opinion turns toward gay marriage without abandoning fidelity and family formation ... [a]nd when public opinion turns toward reproductive freedom and equal rights for women but continues to oppose abortion, it punctures our dismissal of prolife sentiment as a vestige of right-wing sexism. Spin and soundbites won't make the evidence go away. Sooner or later you have to face it."

So how do we face abortion in 2013? Though economic issues are at the top of most everyone's agenda, abortion is not far down the list, for supporters and opponents. At the federal level, we will have intense debate over abortion in health care reform, and any Supreme Court nomination will once again put abortion at center stage. On the state level, restrictions on abortion are proposed in many of the 27 states with prolife legislative majorities. The debate that Roe supposedly ended continues.

Is there any room for optimism? I believe there is.

As a clinical faculty member at the University of Minnesota, I have the privilege of reading essays submitted by students after their OB/GYN rotations. Many thoughtfully reflect on their clinical experiences with abortion. There are admissions of changed perspectives. Most encouraging to me is my volunteer role as faculty advisor to the self-organized Medical Students for Human Life group. They and their colleagues in the Medical Students for Choice group host respectful counterpoint panel discussions that are well-attended and beneficial.

The most recent discussion addressed the now-undeniable evidence that the choice of an abortion significantly increases the risk for preterm birth in a subsequent pregnancy. This effect is at least as strong as maternal smoking -- which we tackle with intensive public-education programs. As the public-policy debate continues, it makes at least as much sense to enact informed-consent requirements and regulations for abortion as it does to put in place gun laws that might decrease the risk of horrific mass shootings.

Who knows what the status of abortion will be in 2033, when my granddaughters are young women? Knowing their grandmother and their mothers, I am sure that they will support the substantial prolife resources already available across this country.

As the 40th anniversary of Roe is celebrated and lamented, I am optimistic, because a growing majority of Americans believe that abortion is not the right answer.

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Steven Calvin is a Minneapolis physician.