Validation of gestational weight gain records on South Carolina birth certificate data

Objective To examine the accuracy of gestational weight gain (GWG) reported on birth certificates (BCs) in comparison with electronic medical records (EMRs), the gold standard. Methods BC data and EMR data were from a random sample of pregnant women who enrolled in CenteringPregnancy program, a type of group-based prenatal care, at three obstetric clinics in South Carolina between 2015 and 2019 (n = 206). Retrospective review of EMR data on patients’ prepregnancy BMI and GWG according to 2009 Institute of Medicine guidelines was conducted. Analyses involved summarizing the variables by their mean and mean differences per data source, and then calculating percent-weighted agreement and kappa statistics. Results The mean values of BMI, delivery weight and total weight gain were similar between BC and EMRs. Data correlation for variables was high for both data sources (height: r = 0.94, prepregnancy weight: r = 0.93, prepregnancy BMI: r = 0.92, delivery weight: r = 0.96, total weight gain: r = 0.60). The BCs slightly underestimated the proportion of women in the normal-weight BMI category but overestimated the proportion in the overweight BMI category. Additionally, BCs slightly overestimated women with inadequate GWG and underestimated those with excessive GWG. Overall, the BC and EMR data were in agreement regarding prepregnancy BMI (weighted-agreement = 90%, Kappa = 0.78) and GWG categories (weighted-agreement = 84%, Kappa = 0.63). Conclusion BC estimates of prepregnancy BMI and GWG categories were similar to those recorded in the EMRs. The South Carolina BC database is a valid database for gestational weight and can provide reasonable estimates for the state in the evaluation of the CenteringPregnancy program.