A runner finishes a marathon and hours later, the runner’s baby is born. Hoorah! What a day for personal celebration, public congratulations.

Except for one detail.

Amber Miller holds her baby at Central DuPage Hospital in Winfield, Ill. Miller felt contractions a few minutes after finishing the Chicago Marathon on Sunday and gave birth hours later to a daughter. (Mark Black/Associated Press)

Those facts turn the story into something more complex and beg the questions: How much exercise is healthy in later stages of a pregnancy? Does anyone outside this family unit have the right to cast judgment?

The first answer: It depends.

In Amber Miller’s case, she had been cleared by a doctor to run for half of the race (she later said she ran and walked). The 27-year-old had run seven previous marathons, including one earlier in this pregnancy and one during a previous pregnancy. For her, the long-distance run was not the jolt to the body that it would have been for the vast majority of us.

For mortals, exercising during pregnancy is now considered, in most part, to be beneficial.

The common medical advice is that with a doctor’s approval, running during pregnancy is fine for women who regularly run and for those with low-risk pregnancies. If there’s a concern that the intensity of the exercise might lead to low birth weight, doctors usually recommend regular ultrasounds and an ample diet.

Beginning a new exercise regime or increasing intensity significantly while pregnant is discouraged.

The second question is debatable. My answer is probably not.

Lots of people disagree. The human interest stories about Miller have mostly been glowing and awe-filled. But much of the reaction has been negative. The Chicago Tribune Web site fielded a barrage of criticism in response to its story on Miller. Some readers accused her of risking stillbirth and brain damage.

This response came despite photos circulating of a beaming Miller, post-marathon and post-delivery, with her apparently healthy infant girl born at 7 pounds 13 ounces.

The distance between the two main reactions — “she’s a hero,” or “she’s a villain” — is similar to that which defined the reaction to elite runner Paula Radcliffe when she said she trained through her pregnancy. (She went on to win the New York City Marathon months after delivering.)

These mothers are either the healthiest among us or the most selfish. Neither one set out to be role models, but their actions have cast them as public figures nonetheless.

Is that fair? Do we have a right to judge how far female athletes push themselves during pregnancy?