Statistical analysis indicated that a certain chromosomal region, which has been implicated in the development of malignancies related to the formation of blood or blood cells, was most affected by tobacco.

Smoking has consequences before and after pregnancy, such as infertility, coagulation problems, obstetric complications (for example, extrauterine pregnancy and placenta previa) and intrauterine growth retardation, according to background information in the article.

However, only indirect data have been published on a possible genotoxic effect on pregnancy in humans. ("Genotoxic" means having the effect of damaging DNA, possibly causing genetic mutation.)

More Chromosomal Abnormalities

Rosa Ana de la Chica, M.Sc., of the Universitat Autònoma de Barcelona, Bellaterra, Spain, and colleagues conducted a study to determine whether maternal smoking has a genotoxic effect on amniotic cells, expressed as an increased chromosomal instability, and analyzed whether any chromosomal regions are especially affected by exposure to tobacco.

Fetal amniocytes (cells of fetal origin in the amniotic fluid) were obtained by routine amniocentesis for prenatal diagnosis from 25 controls and 25 women who smoked 10 or more cigarettes per day for 10 or more years. The women were asked to fill out a smoking questionnaire concerning their smoking habits.

The researchers found that when comparing genetic data between smokers and nonsmokers (controls) there were important differences for the proportion of structural chromosomal abnormalities (smokers: 12.1 percent; controls: 3.5 percent) and, to a lesser degree, for the proportion of metaphases (a phase of cell division) with chromosomal instability (smokers: 10.5 percent; controls: 8.0 percent), as well as for the proportion of chromosomal lesions (smokers: 15.7 percent; controls: 10.1 percent).

Tobacco Has Genotoxic Effect

Statistical analysis indicated that a certain chromosomal region, which has been implicated in the development of malignancies related to the formation of blood or blood cells, was most affected by tobacco.

"It has been suggested that the increase of chromosomal lesions and structural abnormalities or the very existence of an increased chromosomal instability resulting from the genotoxic effect of tobacco could be indicative of an increased cancer risk, and that fragile sites could be responsible for the chromosomal instability observed in cancer cells," the authors write.

"Moreover," they conclude, "an increase of chromosomal instability is associated with an increase in the risk of cancer, especially childhood malignancies."