A nationwide investigation of the impact of the tipped worker subminimum wage on infant size for gestational age

Tipped workers, primarily women of reproductive-age, can be paid a "subminimum wage" 71% lower than the federal minimum wage. We estimated the effects of increasing the state-level tipped worker subminimum wage (federally, $2.13 per hour) on infant size for gestational age in the US as infants born small or large are at risk for poor health across the lifecourse. Utilizing unconditional quantile regression and difference-in-differences analysis of data from 2004 to 2016 Vital Statistics Natality Files (N = 41,219,953 mother-infant dyads), linked to state-level wage laws, census, and antipoverty policy data, we estimated the effect of increasing the subminimum wage on birthweight standardized for gestational age (BWz). Smallest and largest infants are defined as those in the 5th and 95th BWz percentiles, respectively. Increases in the subminimum wage affected the BWz distribution. When compared to a static wage of $2.13 for the duration of the study period, wage set to 100% of the federal minimum ($5.15-$7.25) was associated with an increase in BWz of 0.024 (95% CI: 0.004, 0.045) for the smallest infants and a decrease by 0.041 (95% CI: -0.054, -0.029) for the largest infants. Increasing the subminimum wage may be one strategy to promote healthier birthweight in infants.