Blood Mercury, Lead, and Cadmium in Association With Fetal Ultrasound Measures During Pregnancy in General Population of Indonesian Expectant Mothers

Environmental exposure to heavy metals during pregnancy may adversely impact fetal development, particularly in low- and middle-income countries (LMICs) with limited environmental regulation. This study aimed to assess the relationship between maternal exposure to lead (Pb), cadmium (Cd), and mercury (Hg) and fetal growth parameters in an Indonesian population. A cross-sectional study of 127 pregnant women in their second trimester was conducted. Maternal characteristics and exposure sources were obtained via structured questionnaires. Blood concentrations of Pb, Cd, and Hg were measured using inductively coupled plasma mass spectrometry (ICP-MS). Fetal biometry was assessed by ultrasonography, and z -scores were calculated. Generalized additive models (GAMs) and linear mixed models (LMMs) with restricted cubic splines (RCS) were used to evaluate non-linear associations, adjusting for maternal age and secondhand smoke exposure. Among the 127 pregnant women, the median age was 30 years (range: 20-40 years), and the median blood concentrations of Pb, Cd, and Hg were 6.6, 0.022, and 0.021 µg/L, respectively. Fetal growth Z -scores were as follows: BPD_ z = −0.48 (range: −2.5 to 2.5), HC_ z = −0.38 (range: −2.0 to 2.0), AC_ z = −0.56 (range: −2.5 to 2.0), FL_ z = −0.62 (range: −2.5 to 2.5), and EFW_ z = −0.75 (range: −3.0 to 2.0). Using linear mixed models with restricted cubic splines (RCS), Cd and Hg exposures were significantly associated with increased fetal Z -scores (Cd: β = 1.48, P < .001; Hg: β = .99, P < .001), while Pb showed a negative association (β = −.93, P < .001). Non-smokers exhibited more favorable fetal growth responses compared to those exposed to secondhand smoke. Maternal exposure to heavy metals showed non-linear effects on fetal growth. The findings underscore the need for environmental health monitoring and preventive measures during pregnancy.