Descriptive epidemiology of anophthalmia and microphthalmia, Hawaii, 1986-2001

BACKGROUND: Population-based epidemiologic data on anophthalmia and microphthalmia in the United States are limited and have come mainly from only a few states. The intent of this study was to report on the epidemiology of these eye defects. METHODS: Cases were derived from a population-based birth defects registry in Hawaii and comprised all infants and fetuses with anophthalmia and microphthalmia who were delivered during 1986-2001. Anophthalmia and microphthalmia rates per 10,000 births were determined for selected factors, and comparisons were made by calculating the rate ratios and 95% confidence intervals (CIs). RESULTS: Ninety-six cases of anophthalmia and microphthalmia were identified, with a rate of 3.21 per 10,000 live births. The eye defects were isolated in 5 cases (5.2%), and 24 cases (25.0%) had confirmed chromosomal abnormalities. The risk of anophthalmia and microphthalmia varied over time and was significantly higher for live-born infants with low birth weights and gestational ages. The anophthalmia and microphthalmia rates also varied by maternal race/ethnicity, sex, and plurality, although these differences were not statistically significant. CONCLUSIONS: Anophthalmia and microphthalmia frequently occurred with other birth defects, and the rate was consistent with that found in the literature. The risk of defects differed significantly with time period, birth weight, and gestational age. The impact of many factors on anophthalmia and microphthalmia in Hawaii was frequently consistent with that reported elsewhere.     

Extremely high prevalence of neural tube defects in a 4-county area in Shanxi Province, China

BACKGROUND: In the past, northern China's Shanxi Province has reported the highest incidence of neural tube defects (NTDs) in the world. However, little is known about the epidemiology of NTDs in this area in recent years. METHODS: Data were collected from a population-based birth defects surveillance system in 4 counties that captures information on all live births, stillbirths of at least 20 weeks' gestation, and pregnancy terminations at any gestational age resulting from prenatal diagnosis of a birth defect. We also surveyed mothers of NTD case patients to determine their use of folic acid before and during early pregnancy. RESULTS: During 2003, 160 NTD cases were identified among 11,534 births (NTD birth prevalence = 138.7/10,000 births). The rates of anencephaly, spina bifida and encephalocele were 65.9, 58.1, and 14.7 per 10,000, respectively, and a female predominance was observed among anencephaly cases (male-to-female relative risk [RR], 0.49; 95% confidence interval [CI], 0.30-0.79), but not among spina bifida (RR, 0.90; 95% CI, 0.55-1.45) and encephalocele (RR, 1.03; 95% CI, 0.40-2.69) cases. The percentages of pregnancy termination following prenatal diagnosis of anencephaly, spina bifida, and encephalocele were 50%, 41.8%, and 35.3%, respectively. NTD birth prevalence tended to be higher among mothers aged <20 or > or =30 years (P = .06) and was markedly associated with lower levels of maternal education (P < .001). Among 143 NTD mothers, only 6 (4.2%) used folic acid supplements during the periconceptional period. CONCLUSIONS: The NTD birth prevalence rate in the study area is among the highest worldwide. Folic acid deficiency may be one important risk factor.     

Use of prenatal diagnostic procedures in pregnancies affected with birth defects, Hawaii, 1986-2002

BACKGROUND: Information on the utilization of prenatal ultrasound (US), amniocentesis (AC), and chorionic villus sampling (CVS) in pregnancies affected by birth defects in the United States is limited. The intent of this study was to report on the utilization of these procedures in Hawaii. METHODS: Cases were all infants and fetuses of any pregnancy outcome with birth defects, included in a Hawaii birth defects registry, and delivered during 1986-2002. The rates of prenatal US, AC/CVS, and prenatal diagnosis were calculated. RESULTS: Prenatal US was performed in 76% of the cases and AC/CVS in 14% of the cases. Prenatal diagnosis of a birth defect was made in 16% of the cases. The prenatal US, AC/CVS, and prenatal diagnosis rates in 1998-2002 were 1.5, 1.5, and 1.7 times the rates in 1986-1991, respectively. Among all birth defects, the AC/CVS rate for women aged <35 years was 7% and for women aged > or =35 years was 48%. Among chromosomal abnormalities, the AC/CVS rate for women aged <35 years was 36% and for women aged > or =35 years was 66%. CONCLUSIONS: Only a fraction of the Hawaii birth defects cases was prenatally diagnosed. The rates for prenatal US, AC/CVS, and prenatal diagnosis among pregnancies affected by birth defects were higher in 1998-2002 than in 1986-1991. AC/CVS rates were lower for maternal age <35 years.     

International retrospective cohort study of neural tube defects in relation to folic acid recommendations: are the recommendations working?

Objectives To evaluate the effectiveness of policies and recommendations on folic acid aimed at reducing the occurrence of neural tube defects.Design Retrospective cohort study of births monitored by birth defect registries.Setting 13 birth defects registries monitoring rates of neural tube defects from 1988 to 1998 in Norway, Finland, Northern Netherlands, England and Wales, Ireland, France (Paris, Strasbourg, and Central East), Hungary, Italy (Emilia Romagna and Campania), Portugal, and Israel. Cases of neural tube defects were ascertained among liveborn infants, stillbirths, and pregnancy terminations (where legal). Policies and recommendations were ascertained by interview and literature review.Main outcome measures Incidences and trends in rates of neural tube defects before and after 1992 (the year of the first recommendations) and before and after the year of local recommendations (when applicable).Results The issuing of recommendations on folic acid was followed by no detectable improvement in the trends of incidence of neural tube defects.Conclusions Recommendations alone did not seem to influence trends in neural tube defects up to six years after the confirmation of the effectiveness of folic acid in clinical trials. New cases of neural tube defects preventable by folic acid continue to accumulate. A reasonable strategy would be to quickly integrate food fortification with fuller implementation of recommendations on supplements.     

High rates of neural tube defects in Ukraine

BACKGROUND: Oral consumption of synthetic folic acid can prevent neural tube defects (NTDs), which are some of the most severe congenital anomalies. The prevalence of NTDs in Ukraine and other countries of the former U.S.S.R. has not been well studied. We determined the prevalence of NTD-affected pregnancies in Northwestern Ukraine as background for policy decisions related to flour fortification in this country. METHODS: The Ukrainian-American Birth Defects Program was established in 1999 and conducts population- based surveillance of birth defects in several oblasts (states) of Ukraine. We determined the prevalence of NTDs in the Volyn and Rivne oblasts of Northwestern Ukraine for three years, 2000-2002. RESULTS: There were 75,928 births in the two oblasts in 2000-2002. There were 159 cases of NTDs among live births, stillbirths, and induced abortions. The prevalence of NTDs in the two oblasts in Northwestern Ukraine is 2.1 per 1000 births. CONCLUSIONS: The prevalence of NTD-affected pregnancies we found in Northwestern Ukraine is almost four times what it should be. This prevalence suggests that population folate deficiency is widespread in Ukraine. Universal folic acid fortification of flour milled in Ukraine is urgently needed to end this epidemic of birth defects. Such fortification would be expected to prevent folate deficiency anemia, heart attacks, and strokes.     

Changes in the birth prevalence of selected birth defects after grain fortification with folic acid in the United States: findings from a multi-state population-based study

BACKGROUND: Observational studies and clinical trials have suggested that periconceptional use of folic acid can reduce the risk of birth defects other than neural tube defects (NTDs). Using data reported by states to the National Birth Defects Prevention Network, we examined whether folic acid fortification might have decreased the prevalence of other specific birth defects. METHODS: For each of 16 birth defect categories selected for study, birth prevalence for two time periods was calculated with data submitted from a number of states in 1995-1996 ("pre-fortification") and 1999-2000 ("post-fortification"). Changes in birth prevalence between the two time periods were assessed by calculating prevalence ratios and 95% confidence intervals for each defect, and compared by maternal race/ethnicity and availability of prenatally diagnosed cases. RESULTS: We confirmed previously reported reductions in the birth prevalence of NTDs. In addition, we found modest, yet statistically significant, decreases in the birth prevalence for transposition of the great arteries(12%), cleft palate only (12%), pyloric stenosis (5%), upper limb reduction defects (11%), and omphalocele (21%). More substantial subgroup decreases were observed for renal agenesis among programs that conduct prenatal surveillance (28%), for common truncus among Hispanics (45%), and for upper limb reduction defects among Hispanics (44%). There were modest yet significant increases in the prevalence of obstructive genitourinary defects (12%) and Down syndrome (7%), but not among programs conducting prenatal surveillance for these defects. CONCLUSIONS: These results suggest some modest benefit from the folic acid fortification on the prevalence of a number of non-NTD birth defects.     

Decline in the prevalence of neural tube defects following folic acid fortification and its cost-benefit in South Africa

BACKGROUND: In October 2003 South Africa embarked on a program of folic acid fortification of staple foods. We measured the change in prevalence of NTDs before and after fortification and assessed the cost benefit of this primary health care intervention. METHODS: Since the beginning of 2002 an ecological study was conducted among 12 public hospitals in four provinces of South Africa. NTDs as well as other birth defect rates were reported before and after fortification. Mortality data were also collected from two independent sources. RESULTS: This study shows a significant decline in the prevalence of NTDs following folic acid fortification in South Africa. A decline of 30.5% was observed, from 1.41 to 0.98 per 1,000 births (RR = 0.69; 95% CI: 0.49–0.98; p = .0379). The cost benefit ratio in averting NTDs was 46 to 1. Spina bifida showed a significant decline of 41.6% compared to 10.9% for anencephaly. Additionally, oro‐facial clefts showed no significant decline (5.7%). An independent perinatal mortality surveillance system also shows a significant decline (65.9%) in NTD perinatal deaths, and in NTD infant mortality (38.8%). CONCLUSIONS: The decrease in NTD rates postfortification is consistent with decreases observed in other countries that have fortified their food supplies. This is the first time this has been observed in a predominantly African population. The economic benefit flowing from the prevention of NTDs greatly exceeds the costs of implementing folic acid fortification. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc.     

Birth defects in Arkansas: Is folic acid fortification making a difference?

BACKGROUND: Since 1998, fortification of grain products with folic acid has been mandated in the United States, in an effort to reduce the prevalence of neural tube defects (NTDs). Published reports have shown a reduction in the prevalence of spina bifida since fortification was mandated, but no published studies have reported a reduction in birth defects, other than NTDs, that are postulated to be associated with folic acid deficiency. This study was performed to determine if fortification has reduced the prevalence of NTDs and other birth defects in Arkansas. METHODS: Using data from the Arkansas Reproductive Health Monitoring System, prevalences were computed for thirteen specific birth defects with prior evidence supporting a protective effect of folic acid or multivitamins. Prevalences were calculated using data for live births to Arkansas residents for 1993-2000. Exposure to folic acid fortification was classified by birth year as "pre-fortification" (1993-1995), "transition" (1996-1998) or "post-fortification" (1999-2000). Logistic regression analysis was used to compute crude and adjusted prevalence odds ratios comparing the identified time periods. RESULTS: Prevalences decreased between the pre- and post-fortification periods for spina bifida, orofacial clefts, limb reduction defects, omphalocele, and Down syndrome, but only the decrease in spina bifida was statistically significant (prevalence odds ratio 0.56; 95% confidence interval, 0.37, 0.83). CONCLUSION: In Arkansas, the prevalence of spina bifida has decreased since folic acid fortification of foods was implemented. Similar studies by other birth defects surveillance systems are needed to confirm a preventive effect of fortification for malformations other than spina bifida.     

Effects of folic acid fortification on spina bifida prevalence in Brazil

BACKGROUND: To assess spina bifida birth prevalence changes after folic acid fortification of wheat and maize flours began in Brazil in June 2004. METHODS: Cross‐sectional study of Brazilian live births in 2004 and 2006. Spina bifida birth prevalence from the Live Births Information System (SINASC: Sistema de Informações sobre Nascidos Vivos) in a prefortified period was compared to a period fortified with folic acid in each state. Observed prevalence rates in 2004 were used to calculate the expected prevalence rates in 2006 under the null hypothesis that both were similar. The observed/expected (O/E) ratios were tested by two‐tailed Z‐test. To minimize ascertainment differences among states, the O/E ratio of each one of the 27 Brazilian states was adjusted for the number of births with the Mantel‐Haenszel statistic. RESULTS The reduction in spina bifida birth prevalence in 2006 was 39% (O/E = 0.61; 95% confidence interval [CI], 0.55‐0.67), and 40% (O/E = 0.60; 95% CI, 0.53–0.68), after adjusting for state birth number. This reduction was significant (p < 0.0001), and heterogeneous among states (χ² = 72.96; p < 0.0001). CONCLUSIONS: Using SINASC data, there was a significant reduction in spina bifida birth prevalence in Brazil, probably related to the folic acid food fortification program. Birth Defects Research (Part A) 2011. © 2011 Wiley‐Liss, Inc.     

Trends in the postfortification prevalence of spina bifida and anencephaly in the United States

BACKGROUND: The prevalence of NTDs in the US declined significantly after mandatory folic acid fortification; however, it is not known if the prevalence of NTDs has continued to decrease in recent years relative to the period immediately following the fortification mandate. METHODS: Population‐based data from 21 birth defects surveillance systems were used to examine trends in the birth prevalence of spina bifida and anencephaly during 1999–2000, 2001–2002, and 2003–2004. Prevalence data were stratified by non‐Hispanic White, non‐Hispanic Black, and Hispanic race or ethnicity. Prevalence ratios were calculated by dividing the birth prevalences during the later time periods (2001–2002 and 2003–2004) by the birth prevalences during 1999–2000. RESULTS: During 1999–2004, 3,311 cases of spina bifida and 2,116 cases of anencephaly were reported. Hispanic infants had the highest prevalences of NTDs for all years. For all infants, the combined birth prevalences of spina bifida and anencephaly decreased 10% from the 1999–2000 period to the 2003–2004 period. The decline in spina bifida (3%) was not significant; however the decline in anencephaly (20%) was statistically significant. CONCLUSIONS: While the prevalences of spina bifida and anencephaly in the United States have declined since folic acid fortification in the food supply began, these data suggest that reductions in the prevalence of anencephaly continued during 2001–2004 and that racial and ethnic and other disparities remain. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc.     

Epidemiology of Down syndrome (Trisomy 21), Hawaii, 1986-97

BACKGROUND: The live birth prevalence of Down syndrome is approximately 10 per 10,000 live births in the United States. Down syndrome prevalence has been reported to change over time and to vary by selected demographic factors. METHODS: Data from a population-based birth defects registry in Hawaii involving 363 Down syndrome cases delivered during 1986-97 were used to calculate overall prevalence and to investigate secular trends and differences by selected demographic factors. RESULTS: The total (live birth, fetal death, and elective termination) prevalence was 14.74 per 10,000 live births and fetal deaths. The unadjusted live birth prevalence was 8.67 per 10,000 live births. The adjusted live birth (live births and proportion of elective terminations expected to have resulted in live births) prevalence was 12.59 per 10,000 live births. No significant secular trends were observed for either total prevalence (P = 0.688) or adjusted live birth prevalence (P = 0.604). The total Down syndrome prevalence per 10,000 live births was highest for Far East Asians (22.01), followed by whites (17.06), Filipinos (15.94), and Pacific Islanders (9.21). Prevalence per 10,000 births was higher in metropolitan Honolulu (18.57) than in the rest of Hawaii (14.15). After adjusting for maternal age, however, the differences within the demographic groups were not statistically significant. CONCLUSIONS: The live birth prevalence of Down syndrome in Hawaii during 1986-97 was lower than reported in the literature. Prevalence did not change significantly over time. Any differences in prevalence by maternal race/ethnicity and place of residence appeared to result from differences in maternal age distribution.     

Impact of folic acid food fortification on the birth prevalence of lipomyelomeningocele in Canada

BACKGROUND: Recent studies reported no reduction in the frequency of lipomeningomyelocele (LMMC) in Hawaii and Nova Scotia after the implementation of a folic acid food fortification policy in 1998, while a marked reduction in the prevalence of other NTDs was observed. This study was performed to assess the prevalence of LMMC in Canada in relation to the timing of food fortification. METHODS: The study population included livebirths, stillbirths, and terminations of pregnancies because of fetal anomaly to women residing in seven Canadian provinces, from 1993 to 2002. In each province, the ascertainment of NTD cases relied on multiple sources, and in addition all medical charts were reviewed. The study period was divided into pre‐, partial, and full fortification periods, based on results of red cell folate tests published in the literature. RESULTS: A total of 86 LMMC cases were recorded among approximately 1.9 million live births. The average birth prevalence rate was 0.05/1,000, ranging from a minimum of 0.01/1,000 in 2002 to a maximum of 0.08/1,000 in 1999. There was statistical heterogeneity between years (p = .01), but no pattern compatible with a decrease following fortification. Comparing the full fortification period with the prefortification period, there was a slight but not statistically significant decrease in LMMC birth prevalence. CONCLUSIONS: LMMC seems to be pathogenically distinct from myelomeningocele and more studies are needed to understand the embryologic mechanisms leading to this condition, and the environmental and genetic factors involved in its etiology. Birth Defects Research (Part A), 2008. © 2007 Wiley‐Liss, Inc.     

Epidemiology of gastroschisis in metropolitan Atlanta, 1968 through 2000

BACKGROUND: An increase in the rate of gastroschisis has been documented by birth defects surveillance systems in the United States and in other countries. This study sought to evaluate historical trends in the rate of gastroschisis in Atlanta, Georgia, and to describe the epidemiology of gastroschisis over 33 years. METHODS: Gastroschisis cases were identified through the Metropolitan Atlanta Congenital Defects Program (MACDP) from 1968 through 2000. Poisson regression techniques were used to evaluate trends over time. Data on covariates were compared for three maternal age groups (< or =19, 20-24, and > or =25 years). RESULTS: From 1968 through 1975, the rate of gastroschisis was stable at 0.8 per 10,000 births. After 1975, the rate of gastroschisis was 2.3 per 10,000 births with no significant increase observed from 1976 through 2000. The rate of gastroschisis was six times higher among teenage mothers compared with mothers > or =25 years of age. Affected infants born to teenage mothers were less likely to be born to Black mothers compared to White mothers (rate ratio [RR], 0.4; 95% confidence interval [CI], 0.2-0.6). This was also true for mothers 20-24 years of age (RR, 0.5; 95% CI, 0.3-0.8) but not for mothers 25 years of age or older (RR, 1.6; 95% CI, 0.9-2.7). CONCLUSIONS: An increase in the rate of gastroschisis was observed in the mid-1970s, but no temporal trend has been observed since that time. In light of recent reports of an increasing prevalence of gastroschisis in the United States, continued monitoring of this birth defect is warranted.     

Reduction in orofacial clefts following folic acid fortification of the U.S. grain supply

BACKGROUND: Folic acid fortification in the United States became mandatory January 1, 1998, to reduce the occurrence of neural tube defects (NTDs). We evaluated the impact of folic acid fortification on orofacial clefts using United States birth certificate data for 45 states and the District of Columbia. METHODS: Prevalence ratios (PRs) were calculated comparing orofacial cleft prevalence among births prefortification (1/1990-12/1996) and postfortification (10/1998-12/2002), based on fortification status at conception. The JoinPoint Regression Program and exponentially weighted moving average charts (EWMA) were used to assess the timing of any statistically significant changes in prevalence. Data were stratified by maternal race/ethnicity, age, smoking, and timing of prenatal care. RESULTS: Orofacial clefts declined following folic acid fortification (PR=0.94; 95% CI: 0.92-0.96). The EWMA chart flagged a significant decrease in the fourth quarter of 1998. The JoinPoint graph had one change in slope, with a significant quarterly percent change (-0.34) between 1996 and 2002. The decline in orofacial clefts occurred in non-Hispanic Whites but not other racial/ethnic groups, nonsmokers but not women who reported smoking during pregnancy, and women who received prenatal care in the first trimester but not women who began receiving care later in pregnancy. CONCLUSION: Folic acid fortification in the United States was associated with a small decrease in orofacial cleft prevalence, with the timing of the decline consistent with the introduction of fortification. The decline is much smaller than that observed for NTDs, but nonetheless suggests an additional benefit of this public health intervention.     

NTD prevalences in central California before and after folic acid fortification

BACKGROUND: In many regions, NTD prevalences were already declining prior to folic acid fortification. This study examined whether the declining prefortification (1989–1996) NTD prevalences continued into the postfortification period (1998–2003) in selected California counties. METHODS: This population‐based study used vital statistics data and birth defects registry data that were actively ascertained from medical records. The study population included all live births and stillbirths delivered in central California counties from 1989 to 2003. Cases included deliveries with NTDs during the same time period. RESULTS: For all NTDs combined, the slopes indicated that NTD prevalence was decreasing by 7.5 (slope: ?7.5; 95% CI: ?12.4, ?2.5) cases per 100,000 deliveries per year before fortification, whereas NTD prevalence was no longer decreasing after fortification. Comparison of the difference in the two slopes indicated that the postfortification slope exceeded the prefortification slope by 12.6 (95% CI: 2.6, 22.6) cases per 100,000 deliveries per year. CONCLUSIONS: Annual NTD prevalences in central California did not continue to decrease after implementation of folic acid fortification. Birth Defects Research (Part A) 2008. © 2008 Wiley‐Liss, Inc.     

Prevalence of spina bifida and anencephaly during the transition to mandatory folic acid fortification in the United States

BACKGROUND: In 1992, the United States Public Health Service recommended that all women of childbearing age consume 400 microg of folic acid daily. The Food and Drug Administration authorized the addition of synthetic folic acid to grain products in March 1996 with mandatory compliance by January 1998. The impact of these public health policies on the prevalence of neural tube defects needs to be evaluated. We sought to determine the prevalences of spina bifida and anencephaly during the transition to mandatory folic acid fortification. METHODS: Twenty-four population-based surveillance systems were used to identify 5,630 cases of spina bifida and anencephaly from 1995-99. Cases were divided into three temporal categories depending on whether neural tube development occurred before folic acid fortification (January 1995 to December 1996), during optional fortification (January 1997 to September 1998), or during mandatory fortification (October 1998 to December 1999). Prevalences for each defect were calculated for each time period. Data were also stratified by programs that did and did not ascertain prenatally diagnosed cases. RESULTS: The prevalence of spina bifida decreased 31% (prevalence ratio [PR] = 0.69, 95% confidence interval [CI] = 0.63-0.74) from the pre- to the mandatory fortification period and the prevalence of anencephaly decreased 16% (PR = 0.84, 95% CI = 0.75-0.95). Stratification by prenatal ascertainment did not alter results for spina bifida but did impact anencephaly trends. CONCLUSIONS: The decline in the prevalence of spina bifida was temporally associated with folic acid fortification of US grain supplies. The temporal association between fortification and the prevalence of anencephaly is unclear.     

Trends of selected malformations in relation to folic acid recommendations and fortification: an international assessment

BACKGROUND: Two crucial issues relative to the benefits and impact of folic acid in the prevention of birth defects are whether supplementation recommendations alone, without fortification, are effective in reducing the population-wide rates of neural tube defects (NTDs), and whether such policies can reduce the occurrence of other birth defects. Using data from 15 registries, we assessed rates and trends of 14 major defects, including NTDs, in areas with official recommendations or fortification to assess the effectiveness of recommendations and fortification on a wide range of major birth defects. METHODS: We evaluated surveillance data through 2003 on major birth defects from population-based registries from Europe, North America, and Australia. All included ascertainment of pregnancy terminations (where legal). Trends before and after policies or fortification were assessed via Poisson regression and were compared via rate ratios. RESULTS: Significant changes in trends were seen for NTDs in areas with fortification but not in areas with supplementation recommendations alone. For other major birth defects, there was an overall lack of major trend changes after recommendations or fortification. However, some significant declines were observed for select birth defects in individual areas. CONCLUSIONS: Recommendations alone remain an ineffective approach in translating the known protective effect of folic acid in population-wide decline in NTD rates. Fortification appears to be effective in reducing NTDs. The effect on other birth defects remains unclear.     

Birth defects prevalence among infants of Persian Gulf War veterans born in Hawaii, 1989-1993

BACKGROUND: Gulf War veterans (GWVs) have expressed concern about possible teratogenic exposures. However, epidemiologic studies on birth defects prevalence among their progeny have been limited to military hospitals, anomalies diagnosed among newborns, or self-reported data. To measure the prevalence of selected birth defects among infants of GWVs and nondeployed veterans (NDVs) in Hawaii, using birth defects surveillance records. METHODS: Personal identifiers of 684,645 GWVs and 1,587,102 NDVs and their families were matched against birth certificate records of 99,545 live births reported to the State of Hawaii Department of Health between 1989 and 1993 to identify births to military personnel. These births were matched with records from the Hawaii Birth Defects Program. RESULTS: A total of 17,182 military infants (3,717 GWV infants and 13,465 NDV infants) were identified. Of these, 367 infants (2.14/100 live births) were identified with one or more of 48 major birth defects diagnoses. The prevalence of the 48 birth defects were similar for GWV and NDV infants during the prewar and postwar periods, and among GWV infants who were conceived before and after the Gulf war. CONCLUSIONS: The results must be interpreted with caution because of the small number of affected infants in each birth defects category. This study demonstrated the feasibility of measuring birth defects prevalence among military infants through multiple data linkage. Further, it included live births to parents who had separated from the military, births in civilian hospitals, and birth defects diagnosed through the first year of life.