Influence of exposure to tobacco smoke on serum alpha fetoprotein levels of women in midtrimester pregnancy.

The influence of exposure to tobacco smoke on maternal serum alpha-fetoprotein (AFP) levels at 16 wk gestation was examined. Urinary cotinine levels were used to quantify exposure to tobacco smoke. Significantly higher levels of maternal serum AFP were found in 101 women who had more than 1.0 microgram cotinine/mg urinary creatinine compared with 180 women whose urinary cotinine levels were below this level [(mean +/- SD) 1.23 +/- 0.64 and 1.06 +/- 0.54 respectively; 95 per cent CI of difference of means 0.01-0.31; P < 0.05]. There was a mild albeit statistically significant correlation between urinary cotinine levels and maternal serum AFB (r 0.099; P < 0.05). However, the difference in maternal serum AFP levels between the two groups was not found to be significant, when adjustments for maternal body mass index were made.