The primary concern with pregnancy and chemotherapy is that chemotherapy medications have a potential to cause birth defects, targeting rapidly dividing cells. Limited studies on the subject are available due to concerns about medical ethics. Researchers do not want to deliberately expose developing fetuses to chemotherapy just to see what happens, so they are limited to data on women who chose to receive chemotherapy in pregnancy as a lifesaving measure. Results from these studies have been mixed, showing that some agents are more toxic than others.
Chemotherapy medications typically identify rapidly dividing cells and attempt to interfere with cell division to suppress tumor growth. For a growing fetus, this could present significant programs. Some medications may target cells by specific receptor or type, in which case a developing fetus might be safer, and others cannot cross the placenta. In other instances, pregnancy and chemotherapy can be a bad mix because the drugs may be teratogenic, which indicates that they may cause birth defects.
This is a special concern in the first trimester, when a fetus is rapidly growing and laying the groundwork for the development of the body. In later trimesters, the risk can be less serious, although chemotherapy could still interfere with processes like organ development. The specific risks depend on the particular medication and typically study samples are too small to issue generalized warnings about pregnancy and chemotherapy. For this reason, doctors may be reluctant to recommend chemotherapy in pregnancy, because they don’t know enough about the possible outcomes.
A 2011 study in Northern Europe suggested that the risks of pregnancy and chemotherapy were not as dangerous as previously supposed, and that the bigger concern was premature birth. Women may deliver prematurely in an attempt to spare a fetus from exposure to chemotherapy, or could go into labor prematurely while receiving cancer care. In both cases, the premature delivery can increase the risk of problems later in life for the baby.
A history of chemotherapy is not dangerous for women considering pregnancy, although they may need to wait several months after treatment to allow the drugs to completely clear their systems. In cases where women received radiation or surgery to treat gynecological cancers, they may be infertile as a result of treatment. Pediatricians generally recommend against breastfeeding while on chemotherapy, and advise mothers to consider other resources, like milk banks or formula, to meet infant nutritional needs.
The bottom line with pregnancy and chemotherapy can vary from case to case. The risks of not treating cancer might be higher than those associated with the medications, and some chemotherapy regimens are gentler than others. Patients can meet with obstetricians, pediatricians, and oncologists to talk over their options.
