The "Other" race category on birth certificates and its impact on analyses of preterm birth inequity

Not all individuals self-identify with race categories on birth certificates, selecting "Other" and writing in identities. Our hypothesis was that curating write-in responses in the "Other" race category would contribute to understanding preterm birth inequities.

We analyzed Pennsylvania birth certificates (2006-2014). Two independent coders reviewed each write-in response among those who selected "Other" race. We compared preterm birth rates across subpopulations within "Other" race category using a Monte Carlo simulated Chi-square test.

Among 1,196,125 singleton births, 72,891 (6.1%) exclusively selected "Other" race; Hispanic more often than non-Hispanic individuals (54.5% vs 0.7%), p < 0.0001). Only 545 (0.8%) of Hispanic individuals wrote in responses aligned with preestablished race categories compared to 2,601 (33.2%) of non-Hispanic individuals. Preterm birth rates varied significantly across identities within the "Other" group (P < 0.001).

Utilizing combinations of self-identified race, ethnicity, and continental origin may facilitate public health efforts focused on birth outcome equity.