Spina Bifida Incidence Trends: A Comparative Study of Puerto Rico and the United States

Neural tube defects such as myelomeningocele (MMC) remain a significant public health concern despite prevention efforts. Public health measures have reduced the global MMC incidence, but socioeconomic disparities may limit their impact. Puerto Rico (PR) is a United States (US) territory; however, its socioeconomic landscape is vastly different, which may contribute to differences in MMC incidence. In this study, we aimed to compare the differences in MMC incidence and annual variability between PR and the US.

Data on MMC incidence for the US was obtained from the Centers for Disease Control's National Vital Statistics Reports, and data for PR from the Puerto Rico Birth Defects Surveillance and Prevention System. Annual percentage change (APC) was used to evaluate year-to-year variation, and multiple linear regression analysis was applied to compare incidence rates.

The mean annual MMC incidence in 1996-2020 was 4.88 per 10,000 live births in PR (SD = 1.86), and 1.78 (SD = 0.35) in the US, with an estimated mean difference of 3.11 (p < 0.001). APCs during this period varied significantly, ranging from +200% to -63%. A subgroup analysis after folic acid fortification efforts in PR (1999-2020) showed a persistently elevated incidence in PR (mean = 4.41, SD = 1.33) vs. US (mean = 1.67, SD = 0.25), with an estimated mean difference of 2.72 (p < 0.001).

Despite folic acid fortification and public health interventions, MMC incidence in PR remains higher and more variable. These findings underscore the need for improved disease reporting and targeted, region-specific preventive strategies.