the most common congenital diseases in children is congenital heart disease. factors such as environment, genetic, old maternal age during pregnancy, maternal disease and using medicine in pregnancy, prematuritiy, and specific seasons are significant in the prevalence of disease.materials and methods: a cross sectional study was conducted to investigate the status of children with congenital he...

BACKGROUND Studies of season of birth or season of conception can provide clues about etiology. We investigated whether certain months or seasons of conception are associated with increased risk of autism spectrum disorders, for which etiology is particularly obscure. METHODS The study population comprises 6,604,975 children born from 1990 to 2002 in California. Autism cases (n = 19,238) were...

Matings and litters were studied involving all three-breed crosses (sired by purebred boars) and four-breed crosses (sired by cross-bred boars) from the Duroc, Yorkshire, Landrace and Spotted breeds. There were 764 female mating records and 161 boars used over five sequential breeding seasons. A sample of pregnant gilts was slaughtered each season and the remainder were allowed to carry their l...

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 y...

Season of birth is associated with later outcomes; what drives this association remains unclear. We consider a new explanation: variation in maternal characteristics. We document large changes in maternal characteristics for births throughout the year; winter births are disproportionally realized by teenagers and the unmarried. Family background controls explain nearly half of season-of-birth's...