the wikipedia article claims that the child's illness was radiation induced but the provided source does not.
Just to give you an actual statistic rather than anecdote, among Hiroshima bomb survivors the incidence of birth defects was about 0.9%, or about 500 children in total. I'm not entirely sure how trustworthy this story is.
> among Hiroshima bomb survivors the incidence of birth defects was about 0.9%, or about 500 children in total
From what I understand, this is because the blast spread the radioactive material very far and thin, reducing its concentration in any given area.
In real life the baby died four hours after birth from radiation-induced heart and liver defects: https://en.m.wikipedia.org/wiki/Vasily_Ignatenko
The man’s body absorbed radioactive materials that were slowly unleashed as he disintegrated.