Immigration and Low Birthweight in the US: The Role of Time and Timing Posted on August 24, 2015January 14, 2016 by leahywinter Recommended reading from the March 2015 Log-in and Learn Webinar: Bates, L.M. & Teitler, J.O. (2008). Immigration and low birthweight in the US: The role of time and timing (Working Paper No. 2008-15-FF).