Small-for-gestational-age newborns of female refinery workers exposed to nickel.

OBJECTIVES It has not yet been established whether exposure to nickel (Ni) compounds may cause reproductive toxicity. The objective of this study was to investigate whether women employed under conditions of nickel exposure in early pregnancy were at elevated risk of delivering a newborn small-for-gestational-age (SGA). MATERIALS AND METHODS A register-based study of a well defined population. Data on pregnancy outcome and maternal occupation were obtained from the Kola Birth Registry. Each birth record was assigned a Ni exposure rating category according to maternal occupation at the time of becoming pregnant. Nickel exposure assessment was based on determining the water-soluble Ni subfraction of respirable aerosol fraction obtained by personal monitoring, and/or on measurements of urine Ni concentration. The reference population were the delivering women with background exposure level. The study population consisted of 22 836 births (>27 weeks of gestation) and the SGA infants were defined as below the 10th percentile birth weight for gestational age in the source population. Multiple logistic regression was used to analyze the association of the outcome with the assigned exposure rating category. RESULTS The adjusted odds ratio for Ni-exposed women for giving birth to an SGA newborn was 0.84 (95% CI: 0.75-0.93). CONCLUSIONS We found no adverse effect of maternal occupational exposure to water-soluble Ni in the first part of pregnancy on the risk of delivering an SGA newborn without trisomy. The finding does not exclude a possibility that exposure throughout pregnancy might produce such an effect.