Influence of cigarette-smoking on the result of the triple test.

The aim was to establish whether the risk of trisomy 21 in women smokers undergoing triple test differs to women nonsmokers, whether increased smoking changes the hormonal values, and if the cessation of smoking at the beginning of pregnancy has any influence on the triple test. 1,854 pregnant women were interviewed regarding their smoking habits at the time of the triple test. They were divided into 5 groups: (a) nonsmokers; (b) smokers before pregnancy; (c) 1-5 cigarettes; (d) 6-10; (e) 11 or more. MOM values of AFP, E3 and beta-HCG and Down risk calculated by the triple test were compared within the 5 groups. Increasing smoking was associated with a reduction in MOM values of beta-HCG. Smokers were significantly less likely to be counseled for karyotyping (cut-off level 1:250) than nonsmokers. The values of women who stopped smoking at the beginning of pregnancy were not different to nonsmokers. The results suggest the benefits of inclusion of smoking habits for the calculation of the triple test.