Neural tube defect-specific infant mortality in the United States

Abstract

Background: Significant resources have been devoted to decreasing the rate of neural tube defects (NTDs) in the United States. Both surveillance data and birth records have strengths and limitations for evaluating the outcomes of this resource allocation. Cause-specific infant mortality data can be used as one measure to support evaluation efforts.

Methods: Using period linked birth/infant death data from the National Center for Health Statistics (NCHS), a retrospective analysis was performed to assess the NTD-specific IMR at the national, state, and regional level. NTD-specific IMRs for the United States were calculated from 1996 to 1998; stratified rates by race/ethnicity, maternal age, age at death, and gestational age and birthweight by type of NTD for the total US population were based on three-year aggregates (1996-98); state and regional rates were based on four-year aggregates (1995-98).

Results: Annual US NTD-specific IMRs significantly decreased between 1996 and 1998. Black infants were significantly less likely to die from an NTD when compared to white infants, largely attributed to the high rate of NTD-specific deaths among white Hispanic infants. Infants born to women less than 20 years were more likely than infants born to women in other age groups to die from an NTD. Seventy-six percent of all NTD-specific deaths occurred in the first 23 hours of life. Seventy-four percent of NTD-specific infant deaths were low birthweight and 58 percent were preterm. The Midwest had the highest rate of NTD-specific infant deaths among US regions.

Conclusion: Enhanced prevention efforts are needed to address the disparities in infant deaths due to NTDs between Hispanics and other populations, as well as women under 20 years. Decreases in NTD-specific IMRs may have been impacted by fortification of enriched grain products with folic acid since these efforts were optional beginning in 1996. While there are limitations in cause-specific IMRs, NTD-specific IMRs can be used as one measure to assess the impact of public health interventions aimed at reducing NTDs, respectful of the relatively small numbers.