Bird ST, Toh S, Sahin L, Andrade SE, Gelperin K, Taylor L, Song J, Hampp C. Misclassification in Assessment of First Trimester In-utero Exposure to Drugs Used Proximally to Conception: the Example of Letrozole Utilization for Infertility Treatment. Am J Epidemiol. 2019 02 01; 188(2):418-425.