The prevalence and predictors of anencephaly and spina bifida in Texas Mark A. Canfield a , Lisa Marengo a , Tunu A. Ramadhani a , Lucina Suarez a , Jean D. Brender b and Angela Scheuerle c a Birth Defects Epidemiology and Surveillance Branch, Texas Department of State Health Services, Austin, b Department of Epidemiology and Biostatistics, Texas A&M Health Science Center, School of Rural Public Health, College Station, and c Tesserae Genetics, Dallas, TX, USA Summary Correspondence: Mark A. Canfield, PhD, Birth Defects Epidemiology and Surveillance Branch, Texas Department of State Health Services, 1100 W. 49th Street, Austin 78756, TX, USA. E-mail: mark.canfield@dshs.state.tx.us Canfield MA, Marengo L, Ramadhani TA, Suarez L, Brender JD, Scheuerle A. The prevalence and predictors of anencephaly and spina bifida in Texas. Paediatric and Perinatal Epidemiology 2009; 23: 41–50. Texas shares a 1255-miles border with Mexico and encompasses a variety of ecosys- tems, industries and other potential environmental exposures. The Texas Birth Defects Registry is an active surveillance system which covers all pregnancy outcomes (live- births, fetal deaths and elective pregnancy terminations). This study describes the occurrence and the predictors of neural tube defects (anencephaly and spina bifida) in Texas between 1999 and 2003. Birth prevalence, crude and adjusted prevalence ratios and 95% confidence intervals were calculated using Poisson regression, for each defect, by fetal/infant sex, delivery year and maternal sociodemographic characteristics. Among approximately 1.8 million livebirths, a total of 1157 neural tube defects cases were ascertained by the Registry, resulting in an overall prevalence of 6.33 cases per 10000 livebirths. The prevalences of anencephaly and spina bifida were 2.81 and 3.52 per 10000 livebirths respectively. Prevalences of both defects were highest in Hispan- ics, among mothers living along the border with Mexico, among women of higher parity and among mothers who were 40+ years of age. In addition, the prevalence of each defect was higher among women with no record of prenatal care and among women with less than 7 years of education. Hispanic ethnicity was an important predictor for anencephaly, along with sex, maternal age, parity and border residence. However, only border residence and delivery year were significant predictors for spina bifida. Keywords: neural tube defects, anencephaly, spina bifida, ethnic background, maternal age, parity, geographic area, maternal education. Introduction Neural tube defects (NTD) are major congenital mal- formations resulting from the maldevelopment of the brain (anencephaly) and the spine (spina bifida). Pre- vious studies have shown that the occurrence of anen- cephaly and spina bifida is multifactorial, influenced by a number of maternal and sociodemographic factors. In studies that have included sizeable Hispanic or Mexican-origin populations in the US, the preva- lence of anencephaly, spina bifida or NTD combined has consistently been higher in Hispanics, relative to non-Hispanics or non-Hispanic whites. 1–12 Other factors that have been associated with one or both NTDs in these populations include residence on the border with Mexico, 13,14 Mexican maternal birth- place, 1,4,5,8,10,12 infant sex, 1,3,6,7,15 pregnancy history, 1,3,7 maternal age, 1,3,7,15 parity, 3,4 timing of prenatal care ini- tiation 7,16 and socio-economic status. 6–8,17 In 1991, a large cluster of anencephalic deliveries occurred in Brownsville, a Texas city bordering Mexico. 18 As a result of this significant event and other cluster concerns across the state, the Texas Birth Defects Registry was established in 1993. 19 Targeted surveillance efforts during the 1990s revealed that 41 doi: 10.1111/j.1365-3016.2008.00975.x Paediatric and Perinatal Epidemiology, 23, 41–50. © 2008 The Authors, Journal Compilation © 2008 Blackwell Publishing Ltd.