CIGARETTE-SMOKING AND SPONTANEOUS-ABORTION OF KNOWN KARYOTYPE - PRECISE DATA BUT UNCERTAIN INFERENCES

Data from the first phase (1974-1979) of this New York City case-contr ol study showed that 1) cigarette smoking during pregnancy was associa ted positively with chromosomally normal spontaneous abortion and 2) b oth past and current smoking were associated inversely with trisomic l oss in women under age 30 years and positively in older women. The aut hors used data from two subsequent study phases (1979-1982 and 1982-19 86) to test the stability of these associations over time and the homo geneity between payment groups (private vs. public). Spontaneous abort ions (cases) were classified as chromosomally normal (n = 1,388), tris omic (n = 557), or other chromosomally aberrant (n = 409). Controls (n = 4,165) were women who had registered for prenatal care before 22 we eks' gestation and delivered at 28 weeks or later. For chromosomally n ormal loss, later data gave modest support to prior observations. In t he total sample, current smoking (defined as smoking during the month of the last menstrual period) of 14 or more cigarettes per day was inc reased among chromosomally normal cases in comparison with controls (a djusted odds ratio (OR) = 1.3, 95% confidence interval (CI) 1.1-1.7) a nd in comparison with other aberrant cases (adjusted OR = 1.2, 95% CI 0.8-1.8). Stronger associations in public patients than in private pat ients (adjusted odds ratios of 1.4-1.5 versus 0.8-0.9, respectively) m ight indicate either a mediating effect of social disadvantage or a ch ance fluctuation. For trisomic loss, later data did not support prior observations. Associations between trisomy and past or current smoking did not vary significantly with age in either payment group; assuming no effect modification of age, adjusted odds ratios for smoking in re lation to trisomy were 0.9-1.0.