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

ABSTRACT:

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 'what-if' scenario in which alternative methods are used and attempts to elucidate how method choice affects observed results.

Methods

We constructed two 20-week gestational age cohorts of pregnancies between 2000 and 2005 (New Jersey, Pennsylvania, Ohio, USA) using live birth certificates: one defined preterm birth (PTB) status using CE and one using LMP. Within these, we estimated risk for 4 categories of preterm birth (P

SUBMITTER: Rappazzo KM 

PROVIDER: S-EPMC6128148 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature