ABCB1 and obesity due to melanocortin 4 receptor deficiency: For example, the ABC‐transporters “p‐glycoprotein” (P‐gp, encoded by ABCB1) and “multidrug‐resistant protein‐1′′ (MRP1, encoded by ABCC1) which preferentially export cortisol or corticosterone, respectively, are present in the placenta,31 and ABCB1 mRNA expression is reported to be lower in placentas of pregnancies complicated by severe obesity.32 Further studies are needed to understand the metabolism of corticosterone in pregnancy.