Profiling longitudinal differences in plasma inflammatory factors between the first (T1) and third (T3) trimesters in lean subjects and those with pregravid obesity (BMI >30) showed that independent of maternal BMI, the transition from T1 to T3 was associated with increased levels of several pro-inflammatory (TNFα, S100B, IL-2, IFNβ, IL-17A, IL-18, IL-23) and regulatory (IL-4, IL-10, and IL-13) factors. Here, IFNB1 is linked to obesity due to melanocortin 4 receptor deficiency.