The aim of this epidemiologic study was to point out a relationship between the exposure to products of coal combustion, and complications in pregnancy where one third of causes of stillbirth are still unknown. In the town of Labin (Croatia) a coal-powered thermoelectric power plant is the single major air polluter. We compared the records of miscarriages, premature births and stillbirths in two periods: the control and the exposure period. Data on reproductive loss was based on the records of pregnant women visiting for regular monthly pregnancy checkups. At the time of the epidemiological prospective study, 260 women (n = 138 in the clean period and n = 122 in the dirty period) were considered representative. The data were processed using Chi square and correlation tests. The frequencies of miscarriages and stillbirths were significantly lower in the control than in the exposure period (p < 0.05). Methemoglobinemia and stillbirths recorded over the “exposure” period are significantly higher than in the “control” period (p = 0.0205). The level of methemoglobin in the bloodstream is an worthy biomarker, predictor and precursor of environmental toxics’ adverse effects on the mother and fetus, and can indirectly explain the unrecognized level of fetal methemoglobin. Methemoglobin and heme, having prooxidant properties, also cause the early and late endothelial dysfunction of vital organs. Despite our retrospective epidemiological study findings, we emphasize that the rate of reproductive loss represents a hypothetical risk, which needs to be confirmed with further fetal clinical and anatomopatholgical researches about the effects of methemoglobin catabolism products on the fetal CNS.

The aim of this review is to warn about the effects of methemoglobin and its catabolic products and the toxic effects caused by environmental oxidants that cause high-risk pregnancy and may later impair the health of newborns, children and adolescents.In our study of pregnant women (n = 36) whose methemoglobin level was >1.5 g/l, we took blood samples from their newborns to determine the frequency of sister chromatid exchange (SCE) by cultivating lymphocytes. The research took place at the Department of Biology and Medical Genetics of the School of Medicine in Rijeka (Croatia).The results have shown that no deviation in the SCE frequency was found in either case (1990). We examined data on the health of newborns collected at perinatal hospital departments in Rijeka (Croatia), the preschool office and school service at the Labin Health Center and continued until they were 18 years of age (2008). The statistics obtained by applying the chi-square test show that the incidences of neonatal jaundice (p = 0.034), heart murmur at a later age (p = 0.011) and dyslalia and learning/memory impairments (p = 0.002) were significantly higher than in children of control mothers (n = 19).Depending on the mother's exposure to environmental oxidants, during its development the fetus is more likely to be affected by methemoglobin and hemolysis. Oxidants affect the vascular endothelium of kidneys, brain and other vital organs, because they have the capacity to cross the damaged fetomaternal placental barrier. 'Fetal preeclampsia' is an expected manifestation of the condition. Our research proves our thesis on the pathophysiological relationship between methemoglobinemia and unexplained jaundice and hyperbilirubinemia, heart murmur at a later age, dyslalia and learning and memory impairments that have not exactly been demonstrated yet.

Iron is involved in important vital functions as an essential component of the oxygen-transporting heme mechanism. In this study we aimed to evaluate whether oxidative metabolites from maternal cigarette smoke could affect iron homeostasis in the brain of victims of sudden unexplained fetal and infant death, maybe through the induction of maternal hemoglobin damage, such as in case of methemoglobinemia.

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