Background/Objectives: Phthalates are endocrine disrupting chemicals that may be particularly disruptive during pregnancy. Pregnancy diet is a vehicle for some phthalate exposures. Therefore, we evaluated whether diet quality predicts urinary phthalate/phthalate alternative biomarkers concentrations in pregnant women.Methods: This study includes 427 pregnant women from Champaign-Urbana, Illinois. Alternative Healthy Eating Index (AHEI) scores were estimated from 3-month food frequency questionnaires administered at 34-37 weeks gestation, with higher AHEI scores representing lower chronic diseases risk. We quantified 19 phthalate/phthalate alternative metabolites in cross-pregnancy pools of five first-morning urines in three approximately equal batches based on year of enrollment (2013-2019). In analyses, we used individual metabolites, molar-sums of metabolites of the same parent phthalates (e.g., di(2-ethylhexyl) phthalate (SumDEHP), dibutyl phthalate (SumDBP), di-isononyl phthalate (SumDiNP)) or phthalate replacements (1,2-cyclohexane,dicarboxylic acid diisononyl ester (SumDiNCH), di(2-ethylhexyl) terephthalate (SumDEHTP)). Linear regression models evaluated associations between AHEI and ln-transformed specific-gravity adjusted biomarker concentrations while controlling for demographic/lifestyle characteristics, and stratified by chemical analysis batch.Results: Median AHEI score in these predominantly White, college-educated women was 55.9 (possible 110, range: 24.9-82.4) and varied little across time. Biomarker concentrations were similar to U.S. women and many varied over time: monobenzyl phthalate (MBzP), mono(carboxyisononyl) phthalate (MCNP), mono(3-carboxypropyl) phthalate (MCPP), SumDEHP, and SumDiNP decreased from 2013 to 2019, whereas SumDiNCH and SumDEHTP increased. Women with higher AHEI scores had lower SumDEHP, SumDEHTP, and SumDiNP regardless of time, and MBzP, MCNP, MCPP, and SumDBP only in the earliest batch. The strongest association was between AHEI and SumDEHTP, which decreased by 2.5% for each unit increase in AHEI (95%CI: -3.8, -1.3). Conclusions: In this cohort, pregnant women with high diet quality were the least exposed to plasticizer phthalates/alternatives. While these patterns should be confirmed in other populations, we also noted that associations between diet quality and some phthalates/phthalate alternatives have changed over time.