Associations of Internal-Migration Status with Maternal Exposure to Stress, Lead, and Selenium Deficiency Among Pregnant Women in Shanghai, China

Internal migration and urbanization are occurring on a global scale. Although the risk of exposure to stress/lead/low selenium is assumed to be high among migrant pregnant women, population-based evidence is limited. This study aims to explore the association of internal-migration status with maternal exposure to lead, low selenium, and stress among pregnant women. A total of 1931 pregnant women were investigated in 2010. The internal-migration status was grouped based on their hukou (registered residence) and length-of-residency in Shanghai. Maternal blood lead and serum selenium concentrations were assessed. Life event stress and emotional stress were evaluated using Event-Stress-Scale-for-Pregnant-Women and Symptom-Checklist-90-R-Scale (SCL-90-R), respectively. Logistic regression and general linear models were used to evaluate associations between migration status and lead/stress/low selenium exposure. Compared with the local (with Shanghai hukou and length-of-residency 5years), new migrants (without Shanghai hukou and length-of-residency <2years) had lower social-economic-status (SES), higher lead, life event and emotional stress, and lower selenium levels. After adjusting for SES, new migrants had higher risks of emotional stress (for interpersonal sensitivity of SCL-90-R, OR=2.10, 95% CI 1.22-3.64) and low selenium [lg(selenium): beta=-0.08, 95% CI -0.11, - 0.05], but no significant risks for life event stress and high lead. Compared with the local, migrant pregnant women in big cities may have emotional stress and low selenium independent of SES, and high lead and life event stress dependent on SES.