The fact that Amber Miller did not fall or faint or develop complications while running in the Chicago Marathon is nothing short of a miracle. An ounce of prevention is worth a pound of cure. What on earth was her physician thinking when she was given the green light to half-run half-walk a 26.2 mile marathon? Miller was not your usual runner; she was approximately 39 weeks pregnant.

Although pregnant women are encouraged to maintain an active, healthy lifestyle that includes aerobic exercise, moderation is the order of the day. A woman’s body changes when she becomes pregnant. She has more fluid circulating in her body; hormones from the pregnancy make her ligaments more relaxed, thus she waddles. As the baby enlarges, the diaphragm (aka muscle of respiration) gets pushed up making it difficult for pregnant women to breathe. The heart rate increases and the center of gravity changes as the uterus becomes larger thus, increasing her risk of falling.

Miller participated in 8 previous marathons including one when she was pregnant with her first child. At that time she was 18 weeks. She says that she’s “crazy about running.” As the mother of two sons who were Junior Olympic Track and Field participants, I can relate.  However, where is the voice of reason? Prolonged exercise means an increase in heat production which may or may not affect the fetus. Years ago, pregnant women were discouraged from running or performing any exercise that would increase their core temperature for fear it would adversely affect the fetus. Unborn babies cannot regulate temperature because their brains are not fully developed and it is a special part of the brain that controls temperature.

In recent years, this rule has been relaxed because the medical studies are inconclusive. However, it is not recommended that pregnant women perform more than 45 minutes of continuous exercise and it should be in a temperature controlled environment. This was not the case with Miller. Although she ate frequently and drank water, she ran and walked for over 6 hours, developed contractions and subsequently went into labor. If her physician gave her permission to run at 39 weeks, then perhaps he or she should have accompanied Miller to monitor the process.

26.2 miles at 39 weeks is not a benign act and I certainly hope this will not become a trend among pregnant women.  Can you imagine delivering a baby in the middle of a marathon? It would not be a pretty sight.

Linda Burke-Galloway is an obstetrician-gynecologist and author of The Smart Mother’s Guide to a Better Pregnancy. She blogs at her self-titled site, Dr. Linda Burke-Galloway.

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