Preterm birth is the leading cause of death in children younger than five and a risk factor for brain-based disorders, asthma, and ischemic heart disease. In Canada, approximately 7 to 8% of births are preterm (Abitbol and Rodriguez 2012; Sonnenschein-Van Der Voort et al. 2014; Sutton and Darmstadt 2013) This approach will confirm whether the association between lead and preterm birth is stronger in women with insufficient 25OHD concentrations, which suggests that a considerable proportion of preterm births can be prevented by adequate vitamin D supplementation. Widespread exposures to subtle risk factors can have substantial impacts on the prevalence of preterm birth. The implications of our study extend beyond preterm birth. Lead is a risk factor for preeclampsia and ischemic heart disease (Lanphear et al. 2018; Poropat et al. 2018). UB investigators found that low vitamin D was not a significant risk factor for preeclampsia in the ALSPAC cohort, but it was a risk factor for pre-eclampsia in their meta-analysis (Hyppönen et al. 2014). Examining the joint effect of blood lead and vitamin D may clarify these results. The joint effects of blood lead, air pollution and vitamin D on cardiometabolic health could also be explored in the ALSPAC cohort. These types of studies raise intriguing questions about the joint effect of diet and toxic chemicals, especially for low-income communities burdened by air pollution, toxic chemicals, and inadequate nutrition. References: Abitbol, Carolyn L., and Maria M. Rodriguez. 2012. “The Long-Term Renal and Cardiovascular Consequences of Prematurity.” Nature Reviews Nephrology. Hyppönen, Elina et al. 2014. “Vitamin D and Pre-Eclampsia: Original Data, Systematic Review and Meta-Analysis.” Annals of Nutrition and Metabolism 63(4). Lanphear, Bruce P et al. 2018. “Low-Level Lead Exposure and Mortality in US Adults: A Population-Based Cohort Study.” The Lancet Public Health 3(4). Poropat, Arthur E et al. 2018. “Blood Lead and Preeclampsia: A Meta-Analysis and Review of Implications.” Environmental Research 160. Sonnenschein-Van Der Voort, Agnes M.M. et al. 2014. “Preterm Birth, Infant Weight Gain, and Childhood Asthma Risk: A Meta-Analysis of 147,000 European Children.” Journal of Allergy and Clinical Immunology. Sutton, Perri S., and Gary L. Darmstadt. 2013. “Preterm Birth and Neurodevelopment: A Review of Outcomes and Recommendations for Early Identification and Cost-Effective Interventions.” Journal of Tropical Pediatrics.