Mitochondria respiratory chain CI enzymatic activity was also significantly decreased in placenta from IUGR pregnancies compared to controls (−32.95 ± 10.36%; P < 0.05; Figure 2B; Table S1), despite other MRC complexes (CII, CIV, CI + III and CII + III) were preserved (Figure 2B; Table S1). Here, CD200 is linked to fetal growth restriction.