Women’s athletics have come a long way since girls were encouraged to skip gym class during their periods. For Amber Miller, that long way was exactly 26.2 miles at the Chicago marathon earlier this month. While nearly full-term pregnant. So near term, in fact, that contractions began during the race and she gave birth just hours after crossing the finish line. Headlines quickly asked, “Should pregnant women run marathons?’’ Much discussion developed on medical ethics of exercise during pregnancy.