Comparison of gestational dating methods and implications for exposure-outcome associations: an example with PM2.5 and preterm birth.

OBJECTIVES Estimating gestational age is usually based on date of last menstrual period (LMP) or clinical estimation (CE); both approaches introduce potential bias. Differences in methods of estimation may lead to misclassification and inconsistencies in risk estimates, particularly if exposure assignment is also gestation-dependent. This paper examines a… CONTINUE READING