Background: The aim of the study is to determine the effects of blood lead levels (BLLs) on spontaneous abortion. Methods: A well-matched case-control study was performed at Peking Union Medical College Hospital from 2016 - 2018. Spontaneous abortion cases requiring suction and curettage within 12 weeks gestational age composed the case group. Control group includes pregnancies showing fetal cardiac activity with simultaneous requests for induced abortions matched to case group in age, gravidity, parity, and gestational age.
Results: Three hundred patients with 150 per group were included. Age, gravidity, parity, gestational age and the number of lead exposures, smokers, alcoholic beverage drinkers, and coffee drinkers were not significantly different between the two groups. The mean BLLs were 27.17 μg/L and 17.28 μg/L for the case and control group, respectively (p = 0.000). The odds ratios for spontaneous abortion comparing 5 - 9, 10 - 14, 15 - 24, 25 - 39, and ≥ 40 μg/L with a reference category of < 5 μg/L blood lead 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 (P1 = 0.64, P2 = 0.02, P3 = 0.01, P4 = 0.02, and P5 = 0.00).
Conclusions: Lead contamination and its effect on spontaneous abortion cannot be ignored. During early pregnancy, when BLL is above 10 μg/L, the chance of spontaneous abortion increases compared to BLLs below 5 μg/L. The higher the BLL is, the greater the risk of spontaneous abortion will be.