Effect of maternal smoking during pregnancy on fetus: a cytogenetic perspective

OBJECTIVE: The examination of the genotoxic, cytostatic and cytotoxic effects of smoking during pregnancy.

METHOD: Lymphocyte cultures of peripheral blood were received from 20 women who smoked during pregnancy as well as umbilical cord blood of their newborns. Fluorescence Plus Giemsa staining technique was used in order to perform cytogenetic analyses for three indices, Sister Chromatid Exchanges (SCEs), Proliferation Rate Index (PRI) and Mitotic Index (MI). To reveal any underlying chromosome instability, CPT-11 was used as a positive control.

RESULTS: Newborns whose mothers smoke during pregnancy had increased SCEs levels on their lymphocytes when they were exposed to the mutagenic agent CPT-11 (p < 0.01) compared with newborns lymphocytes exposed to the same agent with non-smoking mothers. Also, mothers smoking during pregnancy had increased SCE levels when their lymphocytes were exposed to CPT-11 (p < 0.01) compared with non smoking mothers whose lymphocytes were exposed to the same agent. In both groups newborns appeared as having decreased (p < 0.01) spontaneous SCEs levels compared with the corresponding SCE rates of their mothers. Decreases of PRIs and MIs are observed in mothers compared to their newborns.

CONCLUSION: Smoking during pregnancy can promote cytogenetic damage in newborn's DNA, causing chromosome instability. The clinical importance of this indirect damage lies in the fact that this type of damage can act synergistically with other environmental and/or chemical mutagenic substances possibly leading to carcinogenicity.