Trace elements zinc, copper, magnesium, and rubidium in pregnant Bulgarian women from an iodine-deficiency endemic region

Trace elements are essential for the biochemistry of the cell. Their reference values have been found to differ considerably in pregnant women stratified by age, place of residence, anthropometric status, and length of pregnancy. In optimal amounts, these elements reduce the risk of pregnancy complications. Subclinical hypothyroidism in pregnancy is associated with adverse maternal and neonatal outcomes. We aimed at determining the effects of Zn, Cu, Mg, and Rb on pregnant women in an iodine deficiency endemic region and find their relationship with the thyroid status and nutrition. We evaluated the iodine status of 61 healthy pregnant women from an endemic region in Bulgaria. TSH and FT4 levels were measured using ELISA. We found elevated levels of copper that differed the most between the first and second trimesters; Cu and TSH were found to be positively correlated ( р <0.05). Lower Cu levels were found in pregnant women consuming pulses more than 2–3 times a week ( р =0.033). The women consuming fish more than 2–3 times a week had higher levels of Rb. We found a pronounced iodine deficiency in more than half of the examined women in the first to third trimesters, without any effect of pregnancy on the ioduria ( р =0.834). All second and third trimester cases were associated with severe ioduria (< 150 µg/L). The high Cu levels were associated with SCH and less pulse consumption during pregnancy in an iodine deficiency endemic area. SCH was found in 24% of the pregnant women in such an area while in 13% of them SCH had progressed to overt hypothyroidism.