ABSTRACT
Preterm labor [delivery after 20 weeks and before 37 weeks of gestation] is the leading cause of prenatal mortality in developed countries. Many women who have preterm labor have abnormally high plasma levels of a-fetoprotein in early pregnancy.This study was designed to evaluate the ability of this biochemical test and a clinical risk factor scoring system to prospectively discriminate pregnancies at high risk for preterm delivery. In nested case control study six-hundred women were studied prospectively from the early second trimester until delivery. There were sixty women in the study group [those with preterm delivery] and sixty women in the control group [those with term delivery]. A plasma level sample was collected during the second trimester, between 17 and 30 week's gestation. Then a-fetoprotein was determined in both groups.The mean AFP level was 196.75 +/- 151.48 IU/mL in the study group and85.98 +/- 55.90 IU/mL in the control group, both of which were statistically significant [p<0.001']. The mean infants age was 33.11 +/- 3.40 weeks in the study group and 38.83 +/- 0.86 weeks in the control group [p<0.001] and mean of birth weight was 1988 +/- 672.33 gr in the study group and 3241.50 +/- 405.98 gr in the control group [p<0.001]. The risk factor scoring system was >10 in 17% of women in the study group and in 8% of women in the control group. The sensitivity, specificity, PPV and NPV of this test was 78%, 65%, 69.10 and 75% respectively. The accuracy of the test, LR+ and LR- were 71%, 2.24 and 0.333 respectively.The combination of measurement of maternal serum AFP in the second trimester associated with a risk factor scoring system provides a more accurate indicator of the risk of preterm delivery and therefore may be of use in targeting prevention strategies