Placental respiratory chain complex activities in high risk pregnancies

Objectives: Mitochondrial oxidative phosphorylation is the key energy source for placental functions and fetal growth. The purpose of this study was to investigate the function of placenta in high risk pregnancies by measuring mitochondrial respiratory chain complex (RCC) activities, and to evaluate the correlation between double test risk ratio and RCC activities. Methods: The placenta samples were collected from 50 pregnant women. The controls consisted of 20 normal uncomplicated pregnancies and the study group (n=30) consisted of preeclampsia (PE), intrauterin growth restriction (IUGR), advanced maternal age (AMA), twins and preterm deliveries. Complexes I, II-III, IV and citrate synthase (CS) activities were measured by spectrophotometric assays. Results: Complexes I, II-III and IV activities were significantly lower in the study group than the controls (p<0.05). Complexes I and II-III activities were significantly reduced in placenta of preterm deliveries compared with the controls (p<0.003). Double test risk ratio was above the cut-off limit (1:300) in 43% of the study group in which decreased complexes I and II-III activities were observed. Conclusions: Impaired placental mitochondria RCC functions can lead to adverse pregnancy outcomes. Pregnant women with high risk in double test should be monitored carefully in terms of PE, IUGR and preterm delivery.