Objective: The objective of this study was to define the most critical gestation period for adverse effects of environmental toxics in terms of preterm delivery (<37 weeks) and low birthweight (<2500 g) in humans.
Study design: From January 1, 1987 to December 31, 1989, 704 women were included in a retrospective epidemiological study. All were from the district of Labin and lived in the vicinity of a coal power plant Plomin 1, Croatia. This plant is the single large source of air pollution in the area. The coal used for fuel is extremely rich with sulfur, 9-11%. Daily, weekly, and monthly consumption of coal and related SO2 emissions were calculated for each pregnant woman from the beginning to the end of pregnancy.
Results: We found that a greater and longer exposure to SO2 emissions during the initial two months of pregnancy resulted in a significantly shorter gestation (end of the first month: -0.0914, p=0.008, end of the second month: -0.0806, p=0.016) and in lower body mass of a newborn (end of the first month: -0.0807, p=0.016, end of the second month -0.0733, p=0.026).
Conclusion: The results of this study confirm the role of inhaled environmental toxics in the early development of human embryo and in adverse pregnancy course caused by permanent oxidative stress, misbalanced production of reactive oxygen species (ROS), reactive nitrogen species (RNS), reactive sulfur species (RSS), and other unfavorable metabolic processes on early embryogenesis, resulting in growth-arrested cells.