Treating pregnant cancer patients with chemotherapy appears not to harm the fetus, but inducing early birth in cancer patients can have harmful results, according to a study released by scientists in Europe.

“The data suggest the children suffer more from prematurity than from prenatal chemotherapy,” Dr. Frederic Amant, a gynecological oncologist at the University Hospitals Leuven in Belgium, said in a presentation at the European Multidisciplinary Cancer Congress in Stockholm.

According to Amant, whose study is apparently the first to focus on the long-term effects of chemotherapy on the mental development of children born to cancer patients, there is no need for patients to have abortions or to delay treatment beyond the first trimester. Amant stressed in his presentation that doctors should avoid inducing early birth if at all possible because only a fraction of the powerful cancer drugs pass through the placenta and into the fetus.

The study followed 70 children from 68 pregnancies where the mother had undergone chemotherapy. The children ranged in age from 18 months to 18 years. Amant said those that were carried to full term were unaffected in terms of the development of their mental processes and heart function. They had normal IQs and healthy hearts. But in 47 of the pregnancies that ended in premature birth, Amant said his research team found significant evidence of cognitive development problems.

“We believe these results do allow us to make a recommendation about chemotherapy in pregnancy: pregnant women with cancer do not need to delay their cancer treatment or terminate their pregnancy,” Dr. Amant said.

He added, however, that further study is still needed to determine other possible long-term effects of chemotherapy on unborn children. He said two areas of focus would be fertility and the likelihood of cancer developing as the study participants grow older.