ELEVATED FREQUENCIES OF HPRT MUTANT LYMPHOCYTES IN CIGARETTE-SMOKING MOTHERS AND THEIR NEWBORNS

Maternal cigarette smoking during pregnancy has been associated with i ncreased perinatal mortality and low birth weight. Several epidemiolog ical studies have demonstrated an association between smoking during p regnancy and an elevated risk of hematopoietic cancer in the child, bu t other studies have failed to confirm this association. We have used an assay for somatic cell mutation to evaluate the in utero effects of exposure to maternal cigarette smoking. Cord blood samples were obtai ned from 10 newborns whose mothers smoked cigarettes during pregnancy and 10 newborns of non-smoking mothers. Blood samples were also obtain ed from 5 of the smoking and 5 of the non-smoking mothers. Smoking sta tus was confirmed in all samples by testing the brood plasma for cotin ine. The frequency of lymphocytes containing mutations at the hypoxant hine phosphoribosyltransferase (hprt) locus was determined with an aut oradiographic assay using cells that had been cryopreserved. The mothe rs who were smokers had a mean frequency (+/- SE) of 3.08 (+/- 0.55) v ariant (mutant) cells per 10(6) evaluatable lymphocytes. The frequency (Vf) in non-smokers was 1.07 (+/- 0.17) x 10(-6). The Vf of newborns of smokers was 2.17 (+/- 0.24) x 10(-6) and newborns of non-smokers ha d a Vf of 0.77 (+/- 0.13) x 10(-6). In both mothers and newborns the d ifference in Vf between smokers and non-smokers was statistically sign ificant(p < 0.05). Maternal and newborn Vfs were significantly correla ted (r = 0.88; p < 0.004), and there was a positive association (r = 0 .86; p < 0.001) between the reported number of cigarettes smoked per d ay and the Vfs. This study provides further evidence that maternal smo king may be hazardous to the future health of children exposed in uter o to mutagenic agents in cigarette smoke.