eager to learn

Since the use of chemotherapy during pregnancy is becoming more common, are the preceived risks considered less severe or less likely to occur within the 'safe' margin of administration in the second and third trimesters only? Do the Ob/GYN and HEM/ONC doctors receive additional training to administer chemotherapeutic drugs to pregnant women or is the practice of chemotherapy administration during pregnancy too recent a practice to have specialized courses devoted to it?

All the literature I have read states chemotherapy treatment during pregnancy should be just as aggressive as chemotherapy treatment in non-pregnant states. I have read mixed opinions concerning when treatment can begin, during the first trimester or only during the second and third trimesters. Many reports state that chemotherapy is safe during the second and third trimesters, and some specific drugs are safe throughout the pregnancy (e.g., tamoxifen). Since chemotherapeutic drugs exert their effect by inhibiting cell division, can they really be considered safe to both the mother and fetus in any trimester? Do you have any experience or additional knowledge concerning the effects of chemotherapy administration during pregnancy? What are your thoughts or opinions about chemotherapeutic drugs and pregnancy?