When cancer is diagnosed in a pregnant woman, life-saving chemotherapy for the mother poses life-threatening concerns for the developing fetus. Depending on the type of cancer and the stage at diagnosis, chemotherapy cannot necessarily be delayed until after delivery. Women diagnosed with acute lymphoblastic leukaemia who decline both termination and chemotherapy often die with the previable fetus in utero. Safe use of chemotherapy, especially during the second and third trimester, have been reported, and pregnant women with cancer can accept therapy without definite neonatal harm. Here, we review the use of chemotherapy in pregnancy by trimester of exposure and summarise neonatal outcomes, including malformations, perinatal complications, and oldest age of neonatal follow-up. We will also discuss the modes of action of the drugs used and look at the multiagent regimens recommended for use during pregnancy.