Amber Miller of Westchester said her doctor gave her clearance to participate in the Sunday event even though she was 38 weeks and 5 days pregnant. She said she felt the baby coming shortly after crossing the finish line with a time of 6 hours and 25 minutes, the Arlington Heights Daily Herald reported Monday.
"A few minutes after I crossed through the finish chute, the contractions were coming a little stronger than I was used too," Miller said. "That's when I figured out what was going on."
Miller said she and her husband, who accompanied her for the marathon, had time to grab some food before heading to Central DuPage Hospital in Winfield.
"The contractions became regular after we finished, so we stopped and grabbed a sandwich and then went to the hospital," she said. "It was the longest day of my life."
Baby June Miller was born at 10:29 p.m. and weighed in at 7 pounds, 13 ounces, WGN-TV, Chicago, reported.
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