Figure 1.

Creation of dataset for analysis of infertility among male Gulf veterans and non-Gulf veterans. ^*After Gulf war deployment (Gulf veterans) or 1 January 1991 (non-Gulf veterans) and before start of main study (1 August 1998). †At least one pregnancy fathered after Gulf war and before 1 August 1997. ‡Congenital malformation of the urogenital system, sterilisation as a result of cancer treatment or injury, and unsuccessful reversal of (elective) sterilisation do not fulfil case definition for infertility