Assessing the value of reviewing all fetal death records for birth defects surveillance, compared to only those with maternal anomaly codes.

Background: The Arizona Birth Defects Monitoring Program (ABDMP) creates case-finding lists of potential birth defects. As part of this, ABDMP includes all fetal death records, in addition to records for mothers and infants with an associated birth defect code. This project aims to understand the value of including all fetal deaths in case-finding, and to assess the impact on the rate of birth defects if all fetal death cases are not reviewed.

Methods: We assessed 2016-2017 fetal death records based on case-finding source and ICD-10 CM codes. We categorized cases by whether they had a hospital discharge ICD-10 CM code indicating a maternal diagnosis for a fetal anomaly (i.e., "O35" code), and compared them to cases reported only by a stillbirth code, meaning that a baby was born deceased, with no reference to birth defects. Positive and negative predictive values were calculated (PPV, NPV, respectively).

Results: For 2016-2017, fetal deaths make up 6% (n = 89) of all confirmed birth defects (n = 1,416), and fetal deaths with no O35 code make up 4% (n = 54) of all confirmed birth defects cases in Arizona. Had cases without an O35 code not been included, 4% (n = 54) of confirmed birth defect cases in Arizona for 2016-2017 would have been missed. The PPV was 68.6%.

Conclusion: The work involved in reviewing the additional 1,000 records per year is warranted by the value noted. It is evident that by including all fetal deaths we capture a more accurate picture of the occurrence of birth defects in Arizona.