Blood lead at currently acceptable levels may cause preterm labour.

OBJECTIVES

Although occupational and environmental exposures to lead have been dramatically reduced in recent decades, adverse pregnancy outcomes have been observed at 'acceptable' levels of blood lead concentrations (≤ 10 μg/dl).

METHODOLOGY

Blood samples were collected from 348 singleton pregnant women, aged 16-35 years, during the first trimester of pregnancy (8-12 weeks) for lead measurement by inductively coupled plasma-mass spectrometry. Subjects were followed up and divided into two groups (preterm and full-term deliveries) according to duration of gestation.

RESULTS

The average (range) and geometric means of blood lead levels were 3.8 (1.0-20.5) and 3.5 μg/dl, respectively. Blood lead level was significantly (p<0.05) higher in mothers who delivered preterm babies than in those who delivered full-term babies (mean±SD: 4.46±1.86 and 3.43±1.22 μg/dl, respectively). Logistic regression analysis demonstrated that a 1 unit increase in blood lead levels led to an increased risk of preterm birth (OR 1.41, 95% CI 1.08 to 1.84).

CONCLUSION

Adverse pregnancy outcomes may occur at blood lead concentrations below the current acceptable level.