LOS ANGELES, CA (Catholic Online) - As published in the Journal of Clinical Oncology, the study has been found to have been "reassuring" because some doctors have wondered if the powerful drugs and radiation, in particular radiation directed near the ovaries or testicles might have long-term effects on the DNA of egg and sperm cells.

There's existing evidence cancer treatments can affect a growing girl's uterus in ways that can cause other pregnancy problems.

"A lot of children are rendered infertile from strong treatments. We know now that depending on the types of treatment they received, they have higher rates of miscarriage (and) higher rates of low birth weight," study author Lisa Signorello, from the International Epidemiology Institute in Rockville, Maryland says.

"As a cancer survivor, the worries extend to the health of your children in many ways."

Researchers followed close to 2,800 childhood cancer survivors in the United States and Canada, giving them regular surveys into adulthood which included questions about pregnancies and births.

Researchers recorded all instances of birth defects in the next generation, and contrasted the chance of having a baby with a birth defect to the dose or radiation or chemotherapy drugs that the cancer survivors had received.

Out of 4,700 babies born to survivors at least five years after they finished treatment, 129, or just under 3 percent had at least one birth defect, including cleft lip and palate, Down syndrome and heart and blood vessel defects.

With the children of women who had survived childhood cancer, those rates were 3 percent after chemo and radiation compared to 3.5 percent when mothers hadn't had those treatments. They were 1.9 percent and 1.7 percent, respectively, in babies born to fathers who'd had cancer.

Drug dosage did not appear to have an impact. Higher doses of chemotherapy drugs or radiation to areas around the testicles and ovaries, such as for treatment of kidney cancer, weren't linked to a greater chance of birth defects than low doses.

About 3 percent of U.S. babies have a birth defect, Signorello and her colleagues wrote. Their study didn't include birth defects that were definitively linked to family history.

"These kinds of studies are very important in terms of counseling for children who have cancer and go through these treatments," Anna Chiarelli, a senior scientist at Cancer Care Ontario in Toronto says. Chiarelli has studied pregnancy outcomes after childhood cancer treatment.

"There has always been that concern, what effect it will have, because of course the child is in a developing stage."

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