Validation of Obstetric Estimate of Gestational Age on U.S. Birth Certificates.

Centers for Disease Control and Prevention, Atlanta, GA. Electronic address: .
American journal of obstetrics and gynecology (Impact Factor: 4.7). 10/2013; 210(4). DOI: 10.1016/j.ajog.2013.10.875
Source: PubMed


The birth certificate variable obstetric estimate of gestational age (OE) has not been previously validated against gestational age based on estimated date of delivery (EDD) from medical records.
We estimated sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and the corresponding 95% confidence intervals (CI) for preterm delivery (<37 weeks gestation) based on OE using EDD-based gestational age as the gold standard. Trained abstractors obtained the EDD from the prenatal record (64.8% in NYC, and 94.6% in Vermont), or, when not available, from the hospital delivery record for two population-based samples: 586 live births delivered in New York City (NYC) and 649 live births delivered in Vermont during 2009. Weights were applied to account for non-response and sampling design.
In NYC, the preterm delivery rate based on EDD was 9.7% (95 % CI 7.6-12.4) and 8.2% (6.3-10.6) based on OE; in Vermont, it was 6.8% (5.4-8.4) based on EDD and 6.3% (5.1-7.8) based on OE. In NYC, sensitivity of OE-based preterm delivery was 82.5% (69.4-90.8), specificity 98.1% (96.4-99.1), PPV 98.0% (95.2-99.2), and NPV 98.8% (95% CI 99.6-99.9). In Vermont, sensitivity of OE-based preterm delivery was 93.8% (81.8-98.1), specificity 99.6% (98.5-99.9), PPV 100%, and NPV 100%.
OE-based preterm delivery had excellent specificity, PPV and NPV. Sensitivity was moderate in NYC and excellent in VT. These results suggest OE-based preterm delivery from the birth certificate is useful for the surveillance of preterm delivery.

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