Increasing prevalence of diabetes during pregnancy in South Carolina

The objective of our study was to examine the prevalence of diabetes during pregnancy at the population level in SC from January 1996 through December 2008.

The study included 387,720 non-Hispanic white (NHW), 232,278 non-Hispanic black (NHB), and 43,454 Hispanic live singleton births. Maternal inpatient hospital discharge codes from delivery (91.59%) and prenatal information (i.e., Medicaid [42.91%] and SC State Health Plan [SHP] [5.98%]) were linked to birth certificate data. Diabetes during pregnancy included gestational and preexisting, defined by prenatal and maternal inpatient International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnostic codes (i.e., 64801-64802, 64881-64882, or 25000-25092) or report on the birth certificate.

Diabetes prevalence from any source increased from 5.02% (95% confidence interval [CI]: 4.82-5.22) in 1996 to 8.37% (95% CI: 8.15-8.60) in 2008. Diabetes prevalence, standardized for maternal age and race/ethnicity from 1996 through 2008, increased from 3.38% (95% CI: 3.29-3.47) to 5.81% (95% CI: 5.71-5.91) using birth certificate data, from 3.99% (95% CI: 3.89-4.10) to 6.69% (95% CI: 6.58-6.80) using hospital discharge data, and from 4.74% (95% CI: 4.52-4.96) to 8.82% (95% CI: 8.61-9.03) using Medicaid data. Comparing birth certificate to hospital discharge, Medicaid, and SHP data, Cohen's kappa in 2008 was 0.73 (95% CI: 0.72-0.75), 0.64 (95% CI: 0.62-0.66), and 0.59 (95% CI: 0.54-0.65), respectively.

An increasing prevalence of diabetes during pregnancy is reported, as well as substantial lack of agreement in reporting of diabetes prevalence across administrative databases. Prevalence of reported diabetes during pregnancy is impacted by screening, diagnostic, and reporting practices across different data sources, as well as by actual changes in prevalence over time.