Impact of smoking on maternal serum markers and prenatal screening in the first and second trimesters

Abstract

Objectives: To examine the effects of smoking on first and second trimester screening markers and to determine the overall impact of these effects on Down syndrome and trisomy 18 risks in first trimester combined, second trimester quadruple and integrated tests.

Methods: Examination of screening records at Women and Infants Hospital during 2006-2008. First trimester pregnancy-associated plasma protein-A (PAPP-A), beta-human chorionic gonadotrophin (hCG) and nuchal translucency and second trimester alpha-fetoprotein (AFP), unconjugated estriol (uE3), hCG and inhibin A (inhA) multiple of the median (MoM) values were extracted from the database along with risk results, smoking status and relevant demographic information.

Results: Smoking led to significantly reduced median levels of first trimester PAPP-A (0.89 MoM) and hCG (0.80 MoM), reduced second trimester uE3 (0.96 MoM) and hCG (0.84 MoM), and increased AFP (1.03 MoM) and inhA (1.39 MoM). After accounting for the differences in age between groups, smokers had higher Down syndrome screen positive rates for the second trimester quadruple test, but not for first trimester combined or integrated tests. Screen positive rates for trisomy 18 were markedly increased in smokers relative to age-matched non-smokers when using first trimester combined or integrated tests.

Conclusion: Smoking leads to increased screen positive rates, especially for trisomy 18 using combined or integrated tests.