[Association of arsenic with unexplained recurrent spontaneous abortion: a case-control study].

Objective: To explore the association of arsenic with unexplained recurrent spontaneous abortion (URSA). Methods: A case-control study was conducted to select URSA patients who were admitted to the Beijing Maternal and Child Health Care Hospital affiliated to Capital Medical University from April to October 2018 as a case group. Women who had a normal pregnancy in the Family Planning Department of the hospital but volunteered to have an abortion were selected as a control group. The case and control group were paired in a 1: 1 ratio. The inclusion criteria of the case group were patients with newly diagnosed recurrent spontaneous abortion who had clinically confirmed more than 2 spontaneous abortions and had 20 weeks prior to pregnancy, excluding patients with recurrent spontaneous abortion caused by abnormal blood coagulation (anti-phospholipid antibody positive), abnormal physiological anatomy (B-ultrasound), abnormal immune factors (anti-nuclear antibody positive, anti-cardiolipin antibody, etc.), genetic chromosomal abnormalities (karyotype analysis) and pathogenic microbial infection. The control group was matched according to the age of the case group (±3 years old) and the gestational age (±2 weeks) to exclude adverse pregnancy outcomes such as stillbirth, congenital malformation, premature delivery and low birth weight infants. A total of 192 subjects were included. Questionnaires were used to collect information of all subjects, and 12 ml of peripheral venous blood was collected to detect blood arsenic levels. Blood arsenic levels were divided into low concentration group (<1.00 μg/L), medium concentration group (1.00-1.50 μg/L) and high concentration group (>1.50 μg/L). The multivariate conditional logistic regression was performed to analyze the relationship between blood arsenic exposure and URSA and explore the influencing factors of blood Arsenic. Results: The geometric mean values of blood arsenic level in the cases group and control group were 1.68 (1.50-1.86) μg/L and 1.26 (1.17-1.37) μg/L, respectively. The blood arsenic level in the case group was significantly higher than that in the control group ( P< 0.05). The results of multivariate conditional logistic regression analysis showed that after adjusting for tobacco exposure during pregnancy, pre-pregnancy body mass index and the effects of residential decoration in past five years, the risk of URSA was higher in the high-concentration group compared with the low-concentration group ( OR =2.56, 95 %CI :1.06-6.24). Conclusion: Blood arsenic may increase the risk of URSA in women of childbearing age.