When radiation doses were high (more than 2.5 Gy), the risk for having a stillbirth or a neonatal death increased 12-fold, they added.
According to Boice, high-dose radiation can damage blood flow to the uterus, which reduces its size. Whether this has an effect on or causes other problems associated with stillbirths isn't clear.
As for men, if radiation had caused reproductive problems it would most likely go unnoticed except in the most heavily exposed populations, since maternal and external factors have a larger role, the researchers said.
"No effect was noted in this cohort of men exposed to testicular irradiation at levels far higher than would be expected from background exposure, diagnostic medical or occupational settings," the study authors wrote.
On the positive side, cancer treatments have changed over time and radiation therapy tends to be more targeted while chemotherapy is now the primary choice of treatment for leukemia, Boice said.
"For current treatment, this [stillbirth] may not be quite the problem as it was in the past," he said.
Dr. Daniel Armstrong, associate chair of pediatrics at the University of Miami Miller School of Medicine, said that "on the one hand, it is not a surprising finding based on what is the known toxicity of radiation therapy."
But, he added, "on the other hand, it is a little reassuring the people who are potentially affected by this is really limited to the group who are getting that particular kind of radiation."
Armstrong said that over the past 20 years there had been a commitment to improve survival and reduce, where possible, the toxicity and the long-term effects of treatment.
"At one point, if your child had cancer, you just wanted to know that they would live, then you wanted to know that they would live well, and now we want to know that they will become adults well," Armstrong said.
"Over the last 15 years, each treatment protocol, t
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