The aim of this study was to assess gastroschisis prevalence in Washington (WA) State in relation to putative risk factors. Gastroschisis prevalence was calculated from the WA State birth cohort during 1987-2006 using an administrative database with birth certificate data linked with hospital discharge records and the ICD-9 procedure code 54.71, which specifies gastroschisis repair. Poisson regression analysis was used to evaluate time trends while adjusting for risk factors. Birth year was included as a linear term. Maternal age, smoking, race, residence in urban versus rural area, geographic region (eastern versus western Washington), paternal age, and infant gender were included as categorical factors. Prevalence ratios were adjusted for birth year and all of the preceding factors. Two hundred and eighty-two infants with gastroschisis were identified. In the adjusted analysis, the prevalence ratio for gastroschisis was 1.1 per year (95% CI 1.08-1.13), indicating an average 10% increase per birth year. Teen mothers were at a higher risk compared to mothers≥25 yr old (adjusted rate ratio [aRR] 8.02; 95% CI 5.30-12.13), as were teen fathers (aRR 2.35; 95% CI 1.48-3.74) compared to fathers≥25 years old. Maternal smoking was associated with a higher risk compared to those who were nonsmokers (aRR 1.58; 95% CI 1.19-2.09). Black mothers had a lower risk compared with white mothers. There was no association with geographic classification of mother's residence. Gastroschisis prevalence has increased in WA, particularly in teen mothers and in smokers. This is not explained by a rise in teenage pregnancies or maternal smoking. Further investigation of factors specific to teenage lifestyle is warranted.