Exposure to pesticide components causes recurrent pregnancy loss by increasing placental oxidative stress and apoptosis: a case-control study

Abstract

We investigated the plasma levels of pesticides components namely polychlorinated biphenyls (PCBs), dieldrin, dichlorodiphenyldichloroethylene (DDE), ethion, malathion, and chlorpyrifos in recurrent pregnancy loss (RPL) cases, and tested their associations with placental oxidative stress (OS) biomarkers [nitric oxide (NO^.), thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), and superoxide dismutase (SOD)] and with placental apoptotic/antiapoptotic indices (Bcl-2 and caspase-3), and evaluated their possible cut-off points to distinguish RPL cases. The study recruited 101 pregnant women divided into; G1 [n = 49, control, normal 1st-trimester pregnancy, normal obstetric history with at least one previous normal live birth], G2 [n = 26, cases with missed abortion (< 3 abortions) before 24 weeks of gestation], and G3 [n = 26, cases with missed abortion (≥ 3 abortions) before 24 weeks of gestation]. The plasma pesticide levels were analyzed by gas chromatography-mass spectrometry. Plasma human chorionic gonadotrophin (HCG), placental OS, Bcl-2, and caspase-3, were analyzed by their corresponding methods and kits. Plasma PCBs, DDE, dieldrin, and ethion levels were significantly higher in RPL cases than in normal pregnancies (p ≤ 0.001). These levels correlated positively with placental OS and apoptosis and negatively with plasma HCG levels. Also, these levels were reliable markers of risk to RPL. Malathion and chlorpyrifos were not detected in any of the study's participants. Pesticides may be risk factors in cases of spontaneous RPL cases. They are associated with an increasing placental OS and placental apoptosis. Specific measures should be taken to decrease maternal exposure to these pollutants' sources, especially in underdeveloped and developing countries.

Figure 1

Clustered bar for the mean of plasma polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDE), dieldrin, and ethion (µg/L) in the 3 studied groups.

Figure 2

Clustered bar for the mean of placental nitric oxide (NO^.), thiobarbituric acid reactive substances (TBARS), glutathione (GSH), superoxide dismutase activity (SOD) in the G2 and G3.

Figure 3

Clustered bar for the mean of placental Bcl-2 and Caspase-3 levels in G2 and G3.

Figure 4

Receiver operating characteristic (ROC) curve for the ability of plasma polychlorinated biphenyl (PCBs), dichlorodiphenyltrichloroethane (DDE), dieldrin, and ethion detect recurrent pregnancy loss (RPL) cases.