Seasonality of birth and implications for temporal studies of preterm birth.

ABSTRACT:

Background

A strength of time-series analyses is the inherent control of individual-level risk factors that do not vary temporally. However, in studies of adverse pregnancy outcomes, risk factors considered time-invariant at the individual level may vary seasonally when aggregated into a pregnancy risk set. To illustrate, we describe the seasonal patterns of birth in Atlanta and demonstrate how these patterns could lead to confounding in time-series studies of seasonally-varying exposures and preterm birth.

Methods

The study cohort included all births in 20-county metropolitan Atlanta delivered during the period 1994-2004 (n = 715,875). We assessed the seasonal patterns of estimated conception and birth for the full cohort and for subgroups stratified by sociodemographic fac

SUBMITTER: Darrow LA 

PROVIDER: S-EPMC3743217 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature