Chemotherapy during pregnancy
Major advances have been achieved with chemotherapy use in pregnancy over the last few decades. After the first trimester, which is the most important in organogenesis ofthe fetus, most chemotherapeutic agents can be used with relative safety.
The transplacental transport of chemotherapeutic agents differ widely, with some agents such as paclitaxel crossing the placenta at a low rate, anthracyclines crossing at an intermediate rate, and carboplatin crossing at a high rate (8, 9). Although some of these agents cross the placenta, the relatively high concentration after 12-14 weeks of pregnancy seems to do little harm to the developing fetus. Certain agents are completely contraindicated including trastuzumab (Herceptin) because of the binding of Her-2 receptors to the kidneys in the fetus, resulting in oligo- or anhydramnios and fetal lung hypoplasia. The antifolates such as methotrexate are also contraindicated.The risk of congenital malformation is directly linked to the gestational age and before 12 weeks there is a risk for abnormalities of the eyes, ears, and blood systems while the risk decreases significantly after complete organogenesis.
Chemotherapy may cause a significant reduction in blood production leading to, among other abnormalities, low platelet counts and a risk for overwhelming infection. When chemotherapy is used, the timing of delivery should be planned carefully. Elective delivery should not be planned within 3 weeks after chemotherapy. For this reason, chemotherapy should not be administered after 37 weeks of gestation due to the risk of spontaneous onset of labour.
Recent work on long-term follow-up of children born to mothers receiving chemotherapy during pregnancy does not indicate an increased risk for congenital abnormalities or mental delay. The number of children with long-term follow-up is still small and the data should be interpreted with caution. Potential risks include a concern for cardiac function in children exposed to anthracyclines during the fetal period. Anthracyclines are commonly used for breast cancer treatment and have a direct effect on cardiac function. In a follow-up study on 17 children, no changes in electrocardiography or echocardiography could be found after the use of anthracyclines.