Season of Conception, Smoking, and Preeclampsia in Norway.

ABSTRACT:

Background

Preeclampsia (PE) is a dangerous and unpredictable pregnancy complication. A seasonal pattern of risk would suggest that there are potentially preventable environmental contributors, but prior analyses have not adjusted for confounding by PE risk factors that are associated with season of conception.

Methods

Seasonal effects were modeled and tested by representing each day of the year as an angle on a unit circle and using trigonometric functions of those angles in predictive models, using "harmonic analysis." We applied harmonic Cox regression to model confounder-adjusted effects of the estimated day of the year of conception on risk of PE for births from the Medical Birth Registry of Norway for deliveries between 1999 and 2009. We also examined effect measure mo

SUBMITTER: Weinberg CR 

PROVIDER: S-EPMC5743488 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature