The majority of fetal organogenesis is completed by 12 weeks of pregnancy, consistent with the literature showing no increased malformation rate for chemotherapy use after the first trimester of pregnancy. The central nervous system continues to develop throughout gestation and after birth. Whether chemotherapy given after the first trimester affects central nervous system maturity and results in developmental delays requires further study. The first authors to provide detailed follow up on children exposed to chemotherapy in utero were Aviles and Niz in 1988. At that time 17 children ranging in age from 4-22 years born to mothers with acute leukemia who received chemotherapy during pregnancy were examined for physical health, growth and development. Each child demonstrated normal growth and development, school performance, intelligence testing, neurological examination, and hematologic evaluation including bone marrow biopsies. This study was expanded twice. First in 1991, to 43 children ranging in age from 3 to 19 years, also after exposure in utero to chemotherapy for maternal hematologic malignancies. All children were normal physically and neurologically. School performances and standardized intelligence testing were not significantly different from controls (unrelated matched children and unexposed siblings). The same authors expanded their study again to a final report of 84 children in 2001, confirming their previous reports that chemotherapy at full doses for an aggressive hematological malignancy can be safely administered. Standardized testing on children exposed to chemotherapy was not repeated for 11 years. Drs. Amant, et al reported developmental outcomes of 70 children in Europe exposed to cancer treatment in utero. The children with developmental delays were concentrated in the group delivered preterm. In this study there was not a control group of unexposed children.