TTi conducted a large nested case-control study examining ondansetron exposure in early pregnancy and risk of structural birth defects using a large, proprietary medical claims database. Logistic regression was used to measure the association between first trimester exposure to ondansetron and risk of structural birth defects, including cardiac defects. Robust statistical approaches were implemented and sensitivity analyses were performed to evaluate the impact of potential confounding by indication and to evaluate potential ascertainment bias and the potential for uncontrolled confounding bias. Our unique approach addressed limitations of prior epidemiological studies and addressed misclassification often present in administrative claims data. Our research was acclaimed by other experts in the field for its outstanding study design and brought to light safety concerns regarding ondansetron use during pregnancy, leading to further investigation into this matter. Two poster presentations based on this work won awards at the annual meeting of ISPOR. As a result of our study (and others that followed), the European Medicines Agency has changed the policy on ondansetron use in pregnancy.