Comparative analyses of umbilical cord lead concentration in term and IUGR complicated neonates

Lead as a toxic heavy metal can readily transfer through the placenta; this condition may increase the risk of lead toxicity for a developing fetus. Therefore, we undertook this study to evaluate the association between umbilical cord blood lead levels and the risk of intrauterine growth restriction (IUGR) occurrence.

A cross-sectional study was done at an academic hospital (Tehran, Iran, 2017). The population study was term and IUGR complicated neonates. Immediately after birth, 3-ml umbilical cord blood was collected in some tubes and sent to a laboratory to assay plasma lead levels. Demographic data related neonates and their mothers were gathered from the medical record. All recorded data were analyzed to compare the cord blood lead levels among normal term and IUGR neonates as the primary outcome.

Totally 152 neonates, 76 in each group with inclusion criteria entered the study. Of all neonates, 71 subjects (47%) were male. The mean (±SD) cord blood lead levels was 6.5 ± 4.2 µg/l. Of all neonates, 102 (67.1%) had high cord blood lead levels (≥5 µg/dl) and 50 subjects (32.8%) had low cord blood lead levels (<5 µg/dl). The mean gestational age, birth weight and head circumference of term neonates were significantly higher than IUGR complicated neonates (p-value = .0001). On the other hand, no significant difference was observed between two groups regarding the mean cord blood lead concentrations (6.2 ± 2.2 and 6.8 ± 5.6 µg/dl; p-value = .855). ANOVA analyses showed no relationships between cord blood lead levels and all assessed qualitative variables except from mother's educational status (in IUGR group; p-value = .048 and in term group; p-value = .010).

Our results highlighted that IUGR occurrence was not associated with fetal blood lead levels alone. Moreover, highly educated mothers had neonates with low blood lead levels, showing that maternal education may be a potentially protective factor against this toxin exposure in newborns. The majority of neonates in the present study had high blood lead concentrations that show a necessity for more efforts and strategies regarding protection against potential deleterious effects of lead toxicity.