Decreasing prevalence of neural tube defects in Utah, 1985-2000.

Abstract

Background: The Utah Birth Defect Network, a statewide surveillance program based in the Utah Department of Health, monitors the occurrence of all neural tube defects (NTDs). Retrospectively and prospectively population-based data was utilized to assess the trend in prevalence for NTDs in Utah from 1985-2000.

Methods: The Utah Birth Defect Network (UBDN) has prospectively identified NTDs in Utah since 1994. NTD cases, including meningomyelocele, meningocele, anencephaly (including exencephaly), encephalocele and craniorachischisis, born to women who are residents of Utah at delivery are reviewed by a pediatric geneticist. All NTDs occurring from 1985-1993 were ascertained retrospectively and documented to be a case. NTDs from all pregnancy outcomes are included (live births, stillbirths and pregnancy terminations) during the entire study period.

Results: NTDs in Utah have decreased significantly between 1985-2000 and remain at the lowest prevalence over the last three of those years. The most significant decrease was seen from 1993-2000. The downward trend was demonstrable for anencephaly and meningomyelocele but not for encephalocele. The proportion of NTDs diagnosed prenatally, as well as those pregnancies terminated after prenatal diagnosis have remained constant, without any evidence of an increasing trend since 1990. However, the proportion of pregnancy terminations occurring prior to twenty weeks gestation has increased significantly since 1990.

Conclusions: The reason for the observed decrease is not known but is likely the result of simultaneous prevention activities locally and nationally, the Utah population's propensity for vitamin and supplement consumption, and recent food fortification. The Centers for Disease Control and Prevention recommended in 1992 that all women in their childbearing years take folic acid daily. The Utah Folic Acid Educational Campaign targeted all women of childbearing years beginning in 1996 with this message. Additionally, fortification of grains was voluntary from 1996, became mandatory in 1998 at which point NTD prevalence declined to its lowest level. These factors may have collectively contributed to the reduction observed in NTD prevalence within Utah, demonstrating the positive impact of an important public health endeavor.