The Interaction between Major Birth Defects and Preterm Birth in Infant Healthcare Expenditures: Implications for Assessments of the Benefits of Prevention

Background: Birth defects and preterm birth are the two leading causes of infant mortality in the United States, often affecting the same infants. Studies of average healthcare costs for preterm birth and birth defects have not adjusted for the interaction between them. Unadjusted average per-child costs can overestimate the magnitude of the preventable burden.

Methods: We used DRG codes in MarketScan® claims data to identify live births during 2013 who had 12 months continuous non-capitated plan enrollment. Preterm birth (<37 weeks) and selected major birth defects (MBDs) were ascertained using ICD-9-CM and DRG codes, which have limitations.  

Results:  Among 56,183 privately insured infants, 1,458 (2.6%) were classified with a MBD, 4,616 (8.2%) were preterm, and 349 (0.6%) infants were born preterm with a MBD. Among non-preterm infants, mean healthcare cost was $58,059 higher with MBDs. Conversely, among infants born preterm, mean cost was $200,263 higher with MBDs. Subtracting the former from the latter, the incremental cost of preterm birth was $142,204 among infants with MBDs. The incremental cost of preterm birth was $41,746 without MBDs. Overall, preterm infants cost $56,016 more on average than non-preterm infants, or $49,341 controlling for MBDs, calculated as the weighted average of the incremental costs of preterm birth among infants with and without MBDs.

Discussion: Adjusting for the interaction of preterm birth and MBDs reduced the mean incremental healthcare cost of preterm birth in this sample by 13-14%. Further analysis of costs of early and late preterm birth among infants with specific MBDs is needed.