Exploration Of Effects Of Heavy Metals On Early Pregnancy Outcomes In Pregnant Women And Its Mechanism

Objective:Influence of environmental pollution on embryonic development gets more and more attention,and heavy metals exposure's effects on early pregnancy outcome is the focus of attention,through two parts of work,the aim of our study is to explore the effects of heavy metal exposure on early pregnancy outcomes in pregnant women and to explore the association between heavy metals and oxidative stress.Methods:The first part is a case-control study conducted at Peking Union Medical College Hospital(PUMCH)in 2016-2018.Women who experienced spontaneous abortion comprised case group,and pregnant women showing fetal cardiac activity who requested an induced abortion were included in control group.Blood and urine specimen were tested for concentrations of lead,arsenic,mercury,cadmium,chromium,selenium.The second part is the further study on a cohort of patients diagnosed with spontaneous abortion in PUMCH from May 1st to July 1st,2019,heavy metal levels in blood.and urine were determined,and oxidative stress level in villi tissue was tested.The oxidative stress level is valued by superoxide dismutase(SOD),catalase(CAT),glutathione peroxidase(GSH-px),nitric oxide(NO)and nitric oxide synthase(NOS)levels.The participants were grouped into two groups based on heavy metal levels.Results:In the first part,a total of 300 patients were enrol led,with 150 in case group and 150 in control group.The blood cadmium levels in the case group and the control gr oup were 0.32±0.28 and 0.22±0.11 respectively(P<0.05);the blood lead levels were 27.21±31.43 and 15.96±12.22 respectively(P<0.05);the urinary chromium levels were 2.67±3.94 and 1.71 ± 2.51 respectively(P<0.05).The odds ratios in the spontaneous abortion of blood cadmium>0.4?g/L,blood lead level?10ug/L,urine chromium>2 ?g/L,gravity<3,parity<2,and history of miscarriage>1 compared were 1.26(1.09,1.85),2.82(2.12,3.08),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),(P<0.05).The odds ratios for spontaneous abortion comparing BLL 5-10,10-15,15-25,25-40,and>or=40?g/L with a reference category of BLL<5?g/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,demonstrating a significant trend(P<0.05).As for the second part,fifteen patients were enrolled.There was a significant difference in CAT between the two groups divided based on arsenic and chromium levels(P<0.05).In addition,the high-level group had higher NO and NOS and lower SOD and GSH-px.Conclusion:Heavy metal exposure in pregnant women has adverse effects on early pregnancy outcomes,among which blood cadmium,blood lead and urinary chromium levels are potential biomarkers of heavy metals that increase the risk of spontaneous abortion;When blood cadmium>0.4?g/L,blood lead ? 10ug/L,urine chromium>2?g/L significantly increased the risk of spontaneous abortion.When BLL?10ug/L,the risk of spontaneous abortion significantly increased,and the higher the blood lead level,the greater the risk of spontaneous abortion.The accumulation of oxygen radicals and the depletion of antioxidants leading to the imbalance of oxidative stress may be important mechanisms by which heavy metals affect embryonic development.