The saying says, “The Devil is in the details”. This idiomatic phrase that means even the grandest project depends on the success of the smallest components. So is the case with low dose ASA for preeclampsia prevention. Currently, the ACOG states, “Low-dose aspirin (LDA) (81 mg/day) prophylaxis is recommended in women at high risk of preeclampsia and should be initiated between 12 weeks and 28 weeks of gestation (optimally before 16 weeks) and continued daily until delivery” (ACOG CO 743; 2018). But the DOSE of LDA is controversial with mounting data that the minimal dose should be 100mg, with leading commentaries pushing for 162 mgs here in the US. We have covered this MANY times on our show. But there is a separate issue here that is often missed. Does it matter WHEN in the day this is taken? Is taking LDA first time in the morning best? What about after lunch? At bedtime? There is data here to guide us. In this episode, we will review the CHRONOBIOLOGIC response of LDA in pregnancy. Yes, that is a real term! This is also reflected in the March of Dimes data. Plus, there is Level I data supporting the best time to take aspirin- and it is fascinating. Listen in for details.