Biomarkers of metal toxicity in embryos in the general population

Abstract

BackgroundWith the development of industrialization, public exposure to toxic metals could occur everywhere, eventually affecting individuals’ reproductive systems and even embryos and leading to early pregnancy loss. The aim of the study was to determine the profile of toxic metal levels in pregnant women in the general population and to identify biomarkers for metal toxicity in embryos.MethodsA case‐control study with pregnant women was conducted at Peking Union Medical College Hospital in 2016‐2018. Women who experienced spontaneous abortion within 12 weeks of gestation comprised the case group, and women with pregnancies showing fetal cardiac activity who requested an induced abortion almost simultaneously were included in the control group. Blood and urine specimen were tested for concentrations of cadmium, chromium, selenium, arsenic, and mercury.ResultsA total of 195 patients were enrolled, with 95 in the case group and 100 in the control group. Significant differences in gravidity, parity, history of miscarriage, mean blood cadmium levels, and mean urine chromium levels were present between the two groups (P1 = 0.013, P2 = 0.000, P3 = 0.000, P4 = 0.002, P5 = 0.046); the odds ratios in the spontaneous abortion with blood cadmium >0.4 µg/L, urine chromium >2 µg/L, gravity <3, parity <2, and history of miscarriage >1 compared with the induced abortion group were 1.26 (1.09, 1.85), 1.56 (1.23, 2.53), 1.39 (1.17, 1.98), 1.72 (1.21, 4.62), and 1.18 (1.06, 1.65), with P‐values of 0.003, 0.031, 0.003, 0.247, and 0.001, respectively.ConclusionBlood cadmium and urine chromium levels are two possible biomarkers of toxic metal embryotoxicity in the general population, which means that in the general population, blood cadmium >0.4 µg/L or urine chromium >2 µg/L might indicate an increased risk of spontaneous abortion.

Heavy metals and metalloids exposure and in vitro fertilization: Critical concerns in human reproductive medicine

“…The odds ratios for spontaneous abortion in five blood lead levels (5–9, 10–14, 15–24, 25–39, and ≥40 μg/L) were 1.58 (0.23–10.90), 3.13 (2.11–9.08), 4.63 (1.45–14.83), 6.33 (1.95–20.56), and 22.56 (4.91–103.66), respectively, indicative of a significant trend (P1 = 0.64, P2 = 0.02, P3 = 0.01, P4 = 0.02, and P5 = 0.00) ( 38 ). Yildrim and Derici ( 42 ) found higher blood Pb levels ( p = 0.038) in pregnant women with history of spontaneous abortion compared to control ( 43 ), while the study by Turan et al ( 43 ) showed significantly increased ( p < 0.001) serum concentrations of Pb and Cd in women with threatened abortion compared to control ( 44 ). Jie et al ( 41 ) demonstrated that blood cadmium >0.4 µg/L or urine chromium >2 µg/L in pregnant women was indicative of a higher risk of spontaneous abortion ( 42 ).…”

“…Out of 30 eligible articles included in the present systematic review, 16 articles focused on clinical studies investigating IVF outcomes (Table 1) (16, 21-35) while 14 articles focused on clinical studies that investigated reproductive concerns (Table 2) (36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49).…”

“…Eight studies investigated association of heavy metals and metalloids with miscarriage/spontaneous abortions ( 37 , 38 , 42 – 45 , 48 , 49 ). Ajayi et al ( 47 ) found significant increase ( p < 0.05) in the serum Pb, and Cd in pregnant women with history of recurrent spontaneous abortion compared with controls ( 48 ).…”

“…Yildrim and Derici (42) found higher blood Pb levels (p = 0.038) in pregnant women with history of spontaneous abortion compared to control (43), while the study by Turan et al (43) showed significantly increased (p < 0.001) serum concentrations of Pb and Cd in women with threatened abortion compared to control (44). Jie et al (41) demonstrated that blood cadmium >0.4 µg/L or urine chromium >2 µg/L in pregnant women was indicative of a higher risk of spontaneous abortion (42) (49). In these 8 studies, Pb and Cd stand out as major reoccurring metals in women with history of spontaneous abortion.…”

Micronutrients in Adverse Pregnancy Outcomes

“…42% of children below five years, 50% of pregnant women-, and 33% women of reproductive age are iron deficient worldwide. 37,38 Among women with miscarriages, 13% higher serum iron levels are seen in 14 weeks of pregnancy. In support of the above findings, serum hepcidin and ferritin concentrations were higher in the first trimester due to possible accumulation of iron in maternal serum because the fetus is not receiving maternal iron through the placenta leading to SA.…”