When is chemotherapy for breast cancer typically initiated during pregnancy?

Chemotherapy for breast cancer during pregnancy is typically initiated once the first trimester is completed. This timing is crucial because the first trimester is a period of significant fetal development, and there are increased risks for the fetus associated with exposure to chemotherapeutic agents during this time. The potential teratogenic effects of chemotherapy drugs and the risk of miscarriage are higher when these agents are administered in the early stages of pregnancy.

Once the first trimester concludes, the fetus has a more developed organ system, and the risks associated with chemotherapy administration decrease significantly. The second and third trimesters present a more favorable opportunity for treatment, as the adverse effects on fetal development are markedly reduced compared to the first trimester. However, it is important to monitor the mother and fetus closely during chemotherapy throughout the remainder of the pregnancy to manage any potential complications and to ensure the safety and well-being of both the mother and the developing baby.