Association of chemotherapy timing in pregnancy with congenital malformation

Chemotherapy during the first trimester of pregnancy should be avoided owing to the risk of congenital malformation. A cohort study by the International Network on Cancer, Infertility, and Pregnancy found that when chemotherapy was initiated after gestational age 12 weeks, the frequency of major congentital malformations was 3.0% (95% CI 1.9-4.6), which was similar to the expected rates in the general population.