Maternal exposure to low-level heavy metals during pregnancy and birth size

Abstract

We evaluated the effect of environmental, low-level exposure to heavy metals during pregnancy, as estimated by urine analysis, on birth size of the newborns. Spot urine samples were collected from unexposed 78 pregnant women in Tokyo during 2007 and 2008. The urinary concentrations of beryllium (Be), copper (Cu), arsenic (As), zinc (Zn), selenium (Se), molybdenum (Mo), cadmium (Cd), tin (Sn), antimony (Sb), and lead (Pb) were measured by ICP-MS. The birthweight (BW), length (BL) and head circumference (HC) of the newborns delivered to the subjects were measured and relationship with urinary metal concentration was examined. The geometric mean concentration of urinary Be, Cu, As, Zn, Se, Mo, Cd, Sn, Sb, and Pb were 0.031, 12.8, 393, 76.9, 37.6, 79.0, 0.766, 0.232, < 0.21, 0.483 μ g g-creatinine^{− 1}, respectively. The mean birth size of the newborn was close to the national average value in Japan. Stepwise multiple regression analysis using birth size as a dependent variable and urinary metal concentrations and covariates as independent variables extracted urinary Cd with a significant negative standardized partial regression coefficient (β) for BW along with gestational age and maternal BMI. For HC, Sn was selected with a negative β. The present study suggested that even a low-level Cd body burden of general population has slight but significant negative effect on BW.

Keywords:

• Pregnant woman
• metal exposure
• urine
• birth size
• cadmium
• tin

Acknowledgment

Part of this study was supported by a grant from the Smoking Research Foundation (Tokyo, Japan).

Notes

*Pre-pregnancy body mass index.

*Based on 3 times standard deviation of 6 travel blank measurements and average creatinine concentration of the present samples (0.80 g L^{− 1}).

**(Number of samples with detectable concentration)/(total number of samples (78)).

*Natural logarithm-transformed value was used.

**Pre-pregnancy body mass index.