Not awesome at all. Irresponsible. She put the baby's health/life at risk. Whether she was walking or running, body temp was high for an extended period of time, and most likely due to her physical exertion during the event, the baby was delivered early under high risk conditions because of Mom's actions.
I'm a female, a runner, and a woman who ran some during pregnancy. What this lady did was stupid. Hopefully the infant doesn't experience any longterm effects.
No way the cost of a marathon registration fee is worth putting your kid at risk like that so late in a pregnancy. Truly appalling.