Women who had pelvic radiation therapy for childhood cancer have an increased risk in delivering a newborn with a lower weight at birth than what might be considered normal, according to a recent study.

The authors, reporting in the American Journal of Obstetrics and Gynecology (Vol. 187, No. 4), also said that women who received chemotherapy as children were not found to have a problem with their pregnancies because of prior treatment.

"We wanted to determine the effect on pregnancy, if any, of prior treatment with radiation therapy or chemotherapy for female survivors of childhood cancer," said lead author Daniel L. Green, MD, at Roswell Park Cancer Institute in Buffalo, N.Y.

"The survival rate of pediatric cancer patients has improved dramatically during the past two decades, with many former patients now achieving young adulthood and beginning to make decisions about marriage and reproduction," Green said.

Because the radiation therapy and chemotherapy used to treat many cancers in children and adolescents may cause mutations in DNA, long-term survivors are concerned about the potential effects on their fertility and on the health of their children, Green said.

Green and his colleagues looked at the medical records and pregnancy outcomes of women in the Childhood Cancer Survivor Study (CCSS). The CCSS is designed to investigate the long-term effects of cancer treatment among survivors of childhood cancer.

The women in the current analysis answered questions regarding attempts to become pregnant, occurrence of pregnancy, age at each pregnancy, duration of each pregnancy, and the outcome. The researchers studied women who were younger than 21 years at diagnosis, between the years of 1970 and 1986.

In the study, 1,915 women reported 4,029 pregnancies. Sisters of the participants were used for comparison.

The researchers looked to see if the type of cancer affected pregnancy outcomes. They found that with the exception of central nervous system (brain and spinal cord) tumors, childhood cancer survivors were not more likely to have miscarriages or stillbirths.

The type of treatment received, however, played a more significant role. Those who received chemotherapy were just as likely to have a normal live birth as those who did not. But women who received radiation in the pelvic area were more likely to bear children who weighed less than 5.5 lbs at birth.

While previous studies have shown similar results with regard to pelvic radiation, the reasons for it are unclear, stated the authors. "We do not know if uterine structure or another factor was changed by irradiation," Green noted. "Regardless, survivors and their physicians must be aware of these issues when guiding a pregnancy to term."

Green said he plans more research to investigate the possible cause for lower birthweight babies in these women. The group also plans to examine to frequency of the development of other problems, such as cancer, among the children of childhood cancer survivors.

Because of the study's finding regarding chemotherapy in these women, Green said he was "reassured to confirm that chemotherapy does not adversely affect pregnancy outcome."