Results: Compared with nonsmoking women, fetal NT was significantly increased and free beta-hCG and PAPP-A levels were significantly decreased in both cigarette and sheesha smokers. There were significant relationships between all three markers and the number of sheeshas consumed per day.
Conclusions: Cigarette and sheesha smoking significantly affect first-trimester markers of Down syndrome (fetal NT, free beta-hCG and PAPP-A). Correction for this effect in women who smoke might improve the effectiveness of first-trimester screening for Down syndrome in these women. The underlying mechanism(s) relating smoking to the changes in first-trimester markers require further studies.