Maternal Serum Cadmium Level During Pregnancy And Its Association With Preterm Birth And Small For Gestational Age(SGA)infants In A Chinese Population

Objective: The present study analyzed the association between maternal serum cadmium level during pregnancy and the risks of preterm birth and small for gestational age(SGA)infants in a large population-based birth cohort study.Methods: The present study analyzed a subsample of the C-ABCS cohort that recruited 3254 eligible mother-and-singleton-offspring pairs.Maternal serum Cd level during pregnancy was measured by graphite furnace atomic absorption spectrometry.This study was to investigate whether maternal serum Cd level during pregnancy is associated with risk of preterm birth and small for gestational age(SGA)infants in a Chinese population.Logistic regression model was used to estimate OR with 95% confidence intervals(CI)with respect to preterm birth and SGA incidence,for adjustment of pre-pregnancy BMI,maternal age,time for collecting serum and average monthly income.According to a previously described methods,maternal serum Cd concentration was classified as different grades based on tertiles and 75 th percentile.The association for different maternal serum Cd concentration during pregnancy and the risk of preterm birth and small for gestational age(SGA)infants was analyzed.Furthermore,The present study analyze the association between maternal serum Cd level at different gestational stage and the risk of preterm birth and small for gestational age(SGA)infants.Results: In the present study,3254 pregnant women were recruited for measurement of serum Cd.The mean serum Cd concentration was 0.89 mg/L(minimum: 0.04 mg/L;maximum: 8.08 mg/L;median: 0.79 mg/L).The rate and odds ratio(OR)for SGA infant were calculated.The rate for SGA infant was 10.6% among subjects with H-Cd(?1.06 ?g/L),significantly higher than 7.5% among subjects with L-Cd(<1.06 ?g/L).OR was 1.45(95% CI: 1.11,1.90;P= 0.007)among subjects with H-Cd.Adjusted OR for SGA infants was 1.43(95% CI: 1.09,1.88;P= 0.007)among subjects with H-Cd.7.3% newborns were with SGA infants among subjects with L-Cd at middle gestational stage.Of interest,11.2% newborns were with SGA infants among subjects with H-Cd at middle gestational stage(OR: 1.59;95% CI: 1.15,2.21;P= 0.006).After adjusting for pre-pregnancy BMI,maternal age,monthly income,parity and gravidity,adjusted OR for SGA was 1.57(95% CI: 1.13,2.19;P= 0.007)among subjects with H-Cd at middle gestational stage.Then,The association for different maternal serum Cd concentration during pregnancy and the risk of preterm birth was analyzed.Based on tertiles,maternal serum Cd concentration was classified as low(L-Cd,<0.65 mg/L),medium(M-Cd,0.65-0.94 mg/L)and high(H-Cd,0.95 mg/L).Results showed the rate of preterm birth among L-Cd,M-Cd and H-Cd was 3.5%,3.8%,and 9.4%,respectively.Subjects with H-Cd had a significantly higher risk for preterm birth(OR: 2.86;95%CI: 1.95,4.19;P < 0.001)than did those with L-Cd.Adjusted OR for preterm birth was 3.02(95%CI: 2.02,4.50;P < 0.001)among subjects with H-Cd compared to subjects with L-Cd.The association between maternal Cd concentration at different gestational age and the risk for preterm birth was further analyzed.The rate of preterm birth among L-Cd,M-Cd and H-Cd was 2.3%,4.0%,and 8.6%,respectively.Subjects with H-Cd had a significantly higher risk for preterm birth(OR: 4.46;95%CI: 2.01,9.93;P < 0.001)than did those with L-Cd.Adjusted OR for preterm birth was 4.51(95%CI: 2.02,10.06;P < 0.001)among subjects with H-Cd compared to subjects with L-Cd at early gestational age.the rate of preterm birth among L-Cd,M-Cd and H-Cd was 4.2%,3.7%,and 9.8%,respectively.Subjects with H-Cd had a significantly higher risk for preterm birth(OR: 2.72;95%CI: 1.71,4.31;P < 0.001)than did those with L-Cd.Adjusted OR for preterm birth was 2.68(95% CI: 1.68,4.27;P < 0.001)among subjects with H-Cd compared to subjects with L-Cd at middle gestational age.Finally,The association for maternal serum cadmium concentration during pregnancy and the risk of different periods preterm birth was analyzed.The rate of moderate preterm infants was 2.2% among subjects with H-Cd,significantly higher than 0.8% among subjects with L-Cd.The OR was 2.94(95%CI: 1.55,5.59;P < 0.001)among subjects with H-Cd.Adjusted OR for moderate preterm birth was 2.95(95%CI: 1.55,5.62;P < 0.001)among subjects with H-Cd.The rate of late preterm infants was 8.4% among subjects with H-Cd,significantly higher than 2.1% among subjects with L-Cd.The OR was 4.27(95%CI: 2.95,6.19;P < 0.001)among subjects with H-Cd.Adjusted OR for late preterm birth was 4.25(95%CI: 2.93,6.17;P < 0.001)among subjects with H-Cd.Conclusion: Maternal cadmium deficiency during pregnancy elevates the risks of preterm birth and small for gestational age(SGA)infants.