Objective: To determine the impact of low dose aspirin (81mg) on markers of maternal inflammation and placental function. Setting: Rural Southern India Population: Nulliparous women with a singleton pregnancy dated by ultrasound who were enrolled in the ASPIRIN (Aspirin Supplementation for Pregnancy Indicated risk Reduction In Nulliparas) Trial. Methods: We performed a case control study of women who delivered prematurely compared to term controls in women enrolled in the ASPIRIN trial. Women were prospectively enrolled in an ancillary observational trial wherein maternal serum was collected and measured between 10 to 13 weeks and 17 to 21 weeks of gestation after initiation of aspirin or an identical placebo. Our primary outcome was the impact of aspirin on markers of placental function and maternal inflammation. Results: From 2016-18 with a total of 666 n women enrolled in this ancillary trial of whom 269 were selected for analyte analysis. Women who received low dose aspirin (LDA) had lower levels of Alpha Feto-Protein (AFP) at 10 to 13 weeks than women who received placebo (Placebo) (LDA 18.3 ng/mL vs 21.4 ng/mL -P 0.001). AFP was similar between the two groups at 17 to 21 weeks. No other differences were seen in in C-Reactive protein or Anti-Mullerian Hormone. Conclusion: Low dose aspirin administration lowers AFP early in pregnancy and may be a marker of Aspirin efficacy. Keywords: maternal serum alpha-fetoprotein (MSAFP), preterm birth, aspirin Tweetable Abstract: Aspirin decreases AFP in the first trimester; a marker associated with poor birth outcomes.