(267) Frequency of diagnosis codes for infant outcomes appearing on maternal health insurance claims

Background: Congenital malformations, preterm birth, and small for gestational age (SGA) are often outcomes of interest for studies of drug safety during pregnancy. While diagnosis codes are available to identify these outcomes within infant health insurance claims, it is important to determine whether these codes also appear in maternal claims at delivery to inform the design of claims-based pregnancy safety studies.

Objectives: To determine how frequently diagnosis codes corresponding to malformations, preterm birth, and SGA for use on infant insurance claims appear on maternal claims.

Methods: Pregnancies were identified in claims from 01 January 2016 through 31 July 2023 using the Optum Dynamic Assessment of Pregnancies and Infants (DAPI) database. Infants were linked to pregnancies using a common unique family insurance ID. The analytic population included pregnancies that were linked to infants, along with the linked infants. Among linked infants, we searched for diagnosis codes for malformations, SGA, and preterm birth during the first 45 days after delivery. Additionally, we searched for diagnosis codes for the same outcomes among pregnancies linked to infants from 45 days before through 45 days after delivery.

Results: A total of 776,826 pregnancies and their linked infants were identified. Of these, 147,571 (19.0%) pregnancy-infant pairs had a diagnosis code for a malformation on the infant claim, while 19,558 (2.5%) had a diagnosis code for a malformation on the maternal claim. Among the 19,558 pregnancies with a code on the maternal claim, about half (51.9%) of the linked infants did not have a malformation code on the infant claim. Similar patterns were found for preterm birth (codes present on 7.6% of infant claims and 0.5% of maternal claims) and SGA (codes present on 4.0% of infant claims and 0.3% of maternal claims). SGA codes were more likely to appear on maternal claims before delivery, whereas malformation and preterm birth codes were more likely to appear on maternal claims after delivery.

Conclusions: These results indicate that diagnosis codes for malformations, preterm birth, and SGA are usually used on infant claims as intended, but sometimes appear on maternal claims. This suggests that researchers designing pregnancy safety studies should consider searching maternal as well as infant claims to improve capture of infant outcomes, particularly malformations. Next steps include exploring specific malformation codes appearing on maternal and infant claims to explore their concordance and determine whether certain malformations are more likely to appear on maternal versus infant claims.