the registries in all states except California (nonmilitary only), births among reservists, National Guard, and former military personnel were eligible, as well as among those on active duty. The study also included comparisons of births to Gulf War veterans before and after deployment. One limitation is that the study relied on availability of unique personal identifiers in military and birth certificate data, which leads to the possibility that some military offspring might be missed among the cases, and that would make the observed prevalence more conservative than the actual. Another is the study’s low power to assess individual defects that are rare. The authors also published the results of the pilot study of their method, which was performed in only Hawaii (Araneta et al., 2000); because the data are incorporated in the larger six-state study, they are not reviewed separately here.
Anecdotal reports raised the possibility of increased prevalence of Goldenhar syndrome, a rare craniofacial abnormality, among children of Gulf War veterans. External features of the syndrome are ear abnormalities, such as microtia, anotia, and preauricular tags. In a case-control study performed by Werler et al. (2005), birth records of infants born with the malformation hemifacial microsomia were examined to determine whether there was an association between Gulf War service of the parents and the birth defect. Hemifacial microsomia was identified in 232 cases from craniofacial clinics in 26 cities and matched to 832 controls by pediatrician and child’s age. Mothers of case subjects and controls were interviewed by telephone in 1996-2002 to identify pregnancy exposures, including military service, particularly in the Gulf War, of the mother or father 5-11 years before the child’s birth. Of the cases, four mothers and 30 fathers had served in the military, as had 10 control mothers and 100 control fathers; of those, four case parents (all in the Army) and 23 control parents (including nine in the Army) had served in the Gulf War. The association with Army service overall was significant (OR 2.4, 95% CI 1.4-4.2), but the association with having served in the Gulf War was not (OR 0.8, 95% CI 0.3-2.3). Study limitations include self-reported military service, small numbers of exposed and limited control for potential confounding. The study by Werler et al. (2005) was described in Volume 4, but the primary or secondary status of the paper was not classified. For the purpose of this review, the study was considered primary.
Additional studies of birth defects are considered secondary either because they rely on self-reports (and thus introduce potential recall bias), because they rely exclusively on birth records from military hospitals and are likely to incompletely ascertain malformations, or because they consider only groups of birth defects. Studying groups of birth defects, although useful in identifying patterns, makes it difficult to determine which specific defects may be increased.
Cowan et al. (1997) examined routinely collected data on all live births in 135 military hospitals in 1991-1993 to compare the frequency of birth defects in children of active-duty Gulf War veterans and nondeployed active-duty veterans. Information on 33,998 infants born to Gulf War deployed veterans (30,151 men and 3847 women) and 41,463 born to nondeployed veterans (32,638 men and 8825 women) was reviewed. The prevalence of any birth defect (that is, any ICD-9-CM code related to congenital malformations) was 7.45% for deployed veterans and 7.59% for nondeployed veterans (RR 0.98, 95% CI 0.93-1.03). There was no significant association between service in the Gulf War and the prevalence of any birth defect for male veterans (OR 0.97, 95% CI 0.91-1.03) or female veterans (OR 1.07, 95% CI 0.94-1.22) after adjustment for mother’s age at delivery, race or ethnicity, and marital status of parent at the time of the Gulf War. The unadjusted OR for having an infant with severe birth defects was 1.03