Sex ratio imbalance in transposition of the great arteries and possible agricultural environmental risk factors.

A significant bias in sex ratio has been documented for several congenital cardiac malformations. Transposition of the great arteries has been associated with a such a bias but no explanation has been proposed for this bias. We evaluated 95 isolated livebirths with transposition of the great arteries cases referred to the Sicilian Registry of Congenital Malformations from 1991 to 1998. We found a statistically significant male bias of 2.8 and this was significantly associated with both maternal and paternal occupational exposure to agricultural chemicals for male infants with transposition, but not for female infants. This study raises new questions about the possible role played by environmental chemicals in relationship to birth defects and to sex ratio imbalance.