Chemo Usually Safe for Pregnant Women with Cancer

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In a finding that is reassuring to pregnant women with cancer, chemotherapy does not appear to pose serious long-term health consequences for the unborn fetus, according to a new study.

Children in the study whose mothers were treated with chemotherapy during pregnancy did just as well developmentally as children in the general population, the researchers said. Children in the study did not appear to be at risk for brain, heart or hearing problems, the study found.

And another result from the study suggested that delivering a baby early in order to start cancer treatment was more harmful to the baby than initiating chemotherapy during pregnancy, the researchers said. Children born prematurely did have an increased risk of lower scores on intelligence and memory tests, compared with children not born prematurely.

"Our findings do not support a strategy of delay in chemotherapy administration or [physician induced] preterm delivery…to avoid harm to the fetus," the researchers wrote in their study.

The findings back up what physicians have been doing in most cases — doctors typically start chemotherapy in a pregnant woman with cancer after her first trimester.

"We try to balance the benefits for mom and for baby," said Dr. Diana Contreras, a gynecological oncologist at Long Island Jewish Medical Center in New Hyde Park, N.Y., who was not involved in the study. The new findings indicate that doctors should let women carry their babies to full term, and not impose a specific birth date on mothers with cancer, Contreras said. (Typical full-term pregnancies last 40 weeks, though babies born at 37 weeks or later are no longer considered premature.)

Cancer in pregnancy

Cancer during pregnancy is rare, and the most common types of cancers are those that occur in women of child-bearing age, including breast and cervical cancer, lymphoma and melanoma, according to the National Institutes of Health.

The study included 68 pregnant women from Belgium, The Netherlands and the Czech Republic who were treated with three to four cycles of chemotherapy during pregnancy. More than two-thirds of the women gave birth prematurely (at less than 37 weeks.)

Some children were enrolled in the study at birth, while others were identified later, and the age range of the total group was 1.5-to-18-years old.

The researchers used a variety of tests to assess the children's general health and development, heart function and mental abilities. Older children also completed hearing, memory, attention and behavior tests.

Most of the children's scores on all of the tests were within normal ranges. Children born prematurely scored lower on tests of cognitive development, although the researchers noted that this is the case in the general population as well. The score for IQ increased about 12 points for each additional month of gestation.

One pair of twins in the study had a severe neurodevelopment delay, but the researchers said it was not likely due to the chemotherapy.

Brain protection

Although the blood-brain barrier of a fetus was once thought to be leaky, allowing compounds in a mother's blood to reach the developing brain, recent data suggests the brain is actually quite protected against chemotherapy drugs, possibility explaining the overall positive results.

While any group of children who are born preterm have lower developmental scores, the researchers noted they cannot rule out the possiblility that the scores were made worse by the chemotherapy.

Because the study was quite small, a larger study in which children are followed for a longer period of time should be conducted to confirm the results, the researchers said.

The study is published online Feb. 10 in the journal The Lancet Oncology.

Pass it on: Chemotherapy during pregnancy does not appear to increase the risk of brain, heart and hearing problems in children.

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Rachael Rettner

Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.