Association between toxic metals, vitamin D and preterm birth in the Maternal-Infant research on environmental chemicals study.

Fisher M, Marro L, Arbuckle TE, Potter BK, Little J, Weiler HA, Morisset AS, Lanphear BP, Oulhote Y, Braun JM, Kumarathasan P, Walker M, Borghese, MM, Ashley-Martin J, Shutt R, Fraser WD. Paediatric and Perinatal Epidemiology. 2023 Mar 2. doi: 10.1111/ppe.12962

Questions: What is the association between prenatal exposure to toxic metals and risk of preterm birth? Do these associations differ depending on a person’s levels of Vitamin D?

Exposure to certain toxic metals like lead may increase the risk of having a preterm birth (PTB). But few studies have examined whether low levels of metals found in most Canadians influences preterm birth risk. Vitamin D, which may have antioxidant activity, may protect against PTB.

What did the researchers do:
Levels of several metals were measured in blood samples collected from MIREC participants during early and late pregnancy. Researchers also measured Vitamin D concentrations in blood samples collected during the first trimester. Using statistical models, they determined whether higher levels of metals were associated with a greater risk of preterm birth. They also investigated whether associations differed according to high or low vitamin D levels.

What did they find:
Overall, approximately 6% of MIREC participants had a preterm birth. High blood lead levels tended to be associated with a nearly 50% increased risk of preterm birth. This risk was even higher for women with low vitamin D concentrations. Women with higher levels of arsenic also tended to have a slightly higher risk of preterm birth.

What does this mean:
This research demonstrates that exposure to certain metals may increase the risk of preterm birth and that individuals with low vitamin D may be more prone to the potentially harmful effects of lead. Given the low number of participants with preterm birth and low vitamin D in MIREC, investigation of these findings in other populations is necessary.

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