Abstract
BACKGROUND: We examined whether hypospadias was associated with several aspects of the diet, including intake of animal products, intake of several nutrients and food groups related to a vegetarian diet and oestrogen metabolism, and diet quality. METHODS: The study included deliveries from 1997 to 2005 that were part of the National Birth Defects Prevention Study. Diet was assessed by food frequency questionnaire during maternal telephone interviews, and two diet quality indices were developed based on existing indices. Analyses included 1250 cases with second- or third-degree hypospadias (urethra opened at the penile shaft, scrotum or perineum) and 3118 male, liveborn, non-malformed controls. All odds ratios (OR) and 95% confidence intervals [CI] were estimated from logistic regression models that included several potential confounders, including energy intake. RESULTS: Intake of animal products was not associated with hypospadias; for example, the adjusted OR for any vs. no intake of meat was 1.0 [95% CI 0.6, 1.6]. Frequency of intake of meat or other animal products was also not associated with hypospadias, nor was intake of iron or several nutrients that are potentially related to oestrogen metabolism. Diet quality was also not associated with hypospadias; the OR for diet quality in the highest vs. lowest quartile for the two diet quality indices were 1.0 [95% CI 0.6, 1.6] and 0.9 [95% CI 0.7, 1.1]. CONCLUSION: This large study does not support an association of a vegetarian diet or worse diet quality with hypospadias.