Introduction:
Environmental exposure to tobacco smoke is a significant threat for human health, where the higher is its degree, the more immature the human organism is. Therefore, the exposure to Tobacco smoke in foetal life exerts unfavourable effects on developing foetus and may cause early and distant results in children.

Material and Methods:
The study comprised 318 children in their first four years of life, treated for various medical conditions. The examined children were divided into two groups, Group 1 – children exposed to Tobacco smoke – and Group 2 – a control group with children from non-smoking families. History data were obtained on the basis of a specially designed questionnaire, used by the doctor in an individual conversation with parent. In each third child from the group 1 cotinine concentration in urine was assayed by the method of high performance liquid chromatography-UV-VIS and the cotinine/creatinine ratio was calculated.

Results of study:
Results demonstrated environmental exposure to tobacco smoke in 173 children (Group 1). Out of them 31.2% were the children whose mothers had smoked also during pregnancy (Subgroup A). The other 119 children from Group 1 were accounted to Subgroup B, i.e., children, where other household members had been smoking cigarettes. A comparative group comprised 143 children from non-smoking families. The results demonstrated then that 17% of all the examined children were those, exposed to tobacco smoke effects already in their foetal life, predisposing them to prematurity and low birth weight. Moreover, it was observed that the young age and lower education level of their parents, together with worse housing conditions, may suggest a predisposing character and role of the mentioned factors.