Methods to estimate gestational age can significantly affect study results - Reply

摘要

Ambrose et al raise 2 important points. First, we did not calculate gestational age (GA) from the last menstrual period (LMP) but assumed that the provided estimate on the state birth certificates was derived following the Centers for Disease Control and Prevention algorithm that is used for the US natality file and that defaults to LMP. We contacted both Florida and Texas Vital Statistics offices and verified that recorded (GA) estimates are indeed the clinical estimate and not solely calculated from the LMP.