How Does the Interaction Between Preterm Delivery and Low Birthweight Contribute to Racial Disparity in Infant...

Area of Science:

• Perinatal epidemiology
• Biostatistics
• Public health

Background:

• Black infants experience twice the mortality rate compared to other racial/ethnic groups in the US.
• Previous mediation modeling suggested preventing low birthweight could reduce this disparity by 75%.
• The interactive role of preterm birth alongside birthweight in this disparity remained unclear.

Purpose of the Study:

• To investigate the interaction between birthweight and length of gestation in contributing to racial disparities in infant mortality.
• To quantify the impact of specific combinations of birthweight and gestational length on racial disparities.

Main Methods:

• Utilized data from over 25 million singleton births in the US National Natality Database (2016-2022).
• Employed Bayesian estimation of potential outcomes to model interactions between birthweight and gestational length.
• Evaluated two models: one with binary (normal/abnormal) classifications and another with five classifications for each factor.

Main Results:

• Normalizing either birthweight or gestational length alone could reduce racial disparity by approximately 75%.
• No additional disparity reduction was observed when both factors were normalized.
• Black infants were 2.76 times more likely to be born extremely preterm with extremely low birthweight, explaining over 60% of the racial disparity.

Conclusions:

• Birthweight and preterm birth interact significantly in driving racial disparities in infant mortality.
• The combination of extremely low birthweight and extremely preterm delivery is a primary driver of this disparity.
• Bayesian estimation of potential outcomes is a valuable tool for investigating complex mediational relationships in public health research.