Maternal occupational/environmental exposure to selected organic solvents and small-for-gestational-age births: a systematic review and meta-analysis.

BACKGROUND

Although studies have suggested an association between organic solvent exposure and small-for-gestational age (SGA), conclusions remain inconsistent due to variations in sample size and study design, with insufficient epidemiological evidence.

OBJECTIVE

We investigated the association between organic solvent exposure and SGA.

METHODS

Following the PRISMA guidelines, searched PubMed, MEDLINE, Embase, and Science Direct databases for cohort and case-control studies. Exposure was classified based on job-exposure matrices (JEMs), expert assessment, or self-reported history. SGA was defined as birth weight <10th centile for gestational age based on a national reference. This systematic review included a total of 11 eligible articles, comprising 15 independent observational studies, of which 10 were cohort studies and 5 were case-control studies. The quality of included studies was assessed using the Newcastle-Ottawa Scale (NOS). Statistical analyses were performed using STATA 14.0 software to calculate the pooled odds ratio (OR) and 95% confidence interval (CI). Heterogeneity was evaluated via Cochran's Q test and I² statistic, with subgroup analysis, sensitivity analysis, and publication bias testing conducted.

RESULTS

Pooled analysis showed that organic solvent exposure was associated with a slight increase in the risk of SGA (OR = 1.15, 95% CI: 1.04-1.26), with moderate heterogeneity (I² = 40.5%, P = 0.052). Subgroup analyses indicated that studies conducted in European and American regions, cohort studies, occupational exposure studies, and high-quality studies (NOS ≥ 7 points) all showed a significant positive association with low heterogeneity (I² = 0), among which the association intensity of occupational exposure was the highest (OR = 1.33). Sensitivity analyses showed that after sequentially excluding each individual study, the pooled OR ranged from 1.12 (95% CI: 1.03-1.22) to 1.19 (95% CI: 1.09-1.29), indicating stable results. Publication bias tests suggested the presence of overall bias (Egger's test P < 0.05), which implies that the pooled effect size might be an overestimation due to the potential absence of small, null-result studies. However, notably, no significant bias was found in the occupational exposure subgroup (Begg's test P = 0.592, Egger's test P = 0.464). Therefore, while the main findings should be interpreted with caution, the results for the occupational exposure subgroup appear to be more robust against publication bias.

SIGNIFICANCE: Maternal occupational/environmental exposure to selected organic solvents may increase the risk of small-for-gestational age, especially in occupationally exposed populations.

IMPACT STATEMENT: This systematic review and meta-analysis, which synthesizes evidence from 15 high-quality studies (10 cohort studies and 5 case-control studies) across Europe and the USA, confirms that maternal occupational/environmental exposure to organic solvents is associated with a 15% increased risk of small-for-gestational-age (SGA) births, with the risk being even higher (33% increase) in occupationally exposed populations. This finding carries substantial implications for public health practice, workplace safety policy, and clinical prenatal care, as outlined below.