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Blood lead at currently acceptable levels may cause preterm labour
  1. Mohsen Vigeh1,
  2. Kazuhito Yokoyama2,
  3. Zahrabigom Seyedaghamiri3,
  4. Atsuko Shinohara2,
  5. Takehisa Matsukawa2,
  6. Momoko Chiba2,
  7. Masoud Yunesian4
  1. 1National Institute of Occupational Safety and Health, Kawasaki, Japan
  2. 2Department of Epidemiology and Environmental Health, Juntendo University School of Medicine, Tokyo, Japan
  3. 3Department of Mother and Child Health, Tehran University of Medical Sciences, Tehran, Iran
  4. 4Center for Environmental Research, Tehran University of Medical Sciences, Tehran, Iran
  1. Correspondence to Mohsen Vigeh, National Institute of Occupational Safety and Health, 6-21-6 Nagao, Tama-ku, Kawasaki 214-8585, Japan; vigeh{at}


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.

  • Lead
  • pregnancy
  • preterm birth
  • gestational age
  • female reproductive effects and adverse pregnancy outcomes
  • women
  • lead

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  • Funding This study was supported by the Japanese National Institute of Occupational Safety and Health, a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science, and Tehran University of Medical Sciences.

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the Ethics Committee under the Vice-chancellor for Research, Tehran University of Medical Sciences.

  • Provenance and peer review Not commissioned; externally peer reviewed.