[The environment, life style and pregnancy outcome].

BACKGROUND

Unproved statement is frequently suggested, that pregnancy outcome in mining districts of Northern Bohemia is damaged due to high level of pollution. The aim of study is to compare the pregnancy outcome of women from the mining district of Teplice (with extremely high air pollution) with that of Prachatice (district with relatively low pollution level) and to evaluate the relative impact of various factors (environmental exposure, lifestyle variables, individual exposures). In the preliminary communication the study design is described and first results are discussed.

METHODS AND RESULTS

About 2260 pregnancies terminated by delivery in Teplice and Prachatice districts from April 1994 till June 1995 were enrolled. In the prospective cohort study all pregnancies terminated during 1994-1997 will be included. Data about reproduction and health history and lifestyle are obtained from questionnaires completed by mothers and medical staff. As indicators of reproductive damage low birth weight (< 2500 g) and premature birth (< 37th week) are used. Preliminary descriptive results obtained during first 14 months of data collection are discussed. Prevalence of low birth weight was 8.8% in the district of Teplice but only 4.0% in Prachatice (P < 0.001). It is 6.2% and 3.4% for prematurity (P < 0.01). However, 14.1% Gypsy births were found in Teplice whereas only 2.9% in Prachatice (P < 0.001). Prevalence of low birth weight is 23.6% and that of prematurity 13.4% among Gypsy births. Significant linear relationship of low birth weight (P < 0.0001) and prematurity (P < 0.0001) with number of cigarettes smoked by mother at early pregnancy was found. Significantly higher proportion of Teplice mothers smokes significantly more cigarettes (P < 0.0001). Relative risk of premature birth of infants conceived in winter by smoking mothers is 3.2 times higher for non-Gypsies (P < 0.0001) and 6.5 times higher by Gypsies (P < 0.0001).

CONCLUSIONS

Differences of prevalence of low birth weights and prematurity between Teplice and Prachatice districts would be explained partly by differences in ethnic structure and smoking habits. However, the difference remains significant statistically just after exclusion of both factors mentioned. The adverse effect of the Winter conception period on the prematurity prevalence could be due to synergistic effect of smoking and environmental load (increased level of pollutants in winter period); simultaneous action of both factors may exceed the threshold of protective mechanisms.