Twenty-eight of the women were pregnant with their first child, eight with their second, and the rest were on their third, fourth or fifth pregnancies.
In general, these women had outcomes similar to more than 9000 women who never had cancer, Dr. Sharon Lie Fong, at Erasmus Medical Center in Rotterdam, The Netherlands, and her colleagues found.
However, the six women previously treated with abdominal radiation appear to be the exception.
Although just two of the six bled severely after childbirth, percentage-wise this represents a higher rate (33%) of severe bleeding cases relative to that seen in the general population where just 5% bled after childbirth.
The researchers urge health care providers to be aware of this risk when treating women cancer survivors during pregnancy, particularly since this finding "has not been reported so far in childhood cancer survivors," Lie Fong's team notes in the journal Human Reproduction.
Notably, the women's very young age at cancer treatment - about 7 years old on average - did not seem to prevent harmful effects of radiation to their small, pre-puberty uteruses.
The six women who received radiation to the abdomen in childhood also delivered their babies an average of 4 weeks earlier than their cancer-free peers. However, babies born to the cancer survivors, including those previously treated with abdominal radiation, appeared as healthy as those born to cancer-free moms.
Due to the increased risks noted in this study, Lie Fong's team discourages home birth and encourages heightened prenatal care for women who received abdominal radiation for childhood cancer.