Objective: To investigate whether abnormal immune system activation is involved in the pathogenesis of some instances of impaired fetal growth, we compared tumor necrosis factor-alpha levels in midtrimester amniotic fluid samples obtained from appropriate-for-gestational-age and small-for-gestational-age pregnancies.
Study design: In a case-control study with the sensitive and specific WEHI cell assay, bioactive tumor necrosis factor-alpha levels in amniotic fluid samples from 24 gestations resulting in small-for-gestational-age infants were compared with levels in 35 samples obtained from gestations resulting in the birth of a term, appropriate-for-gestational-age infant. The two groups were not significantly different with regard to indication for amniocentesis, maternal age, race, smoking history, parity, or other factors.
Results: Elevated amniotic fluid tumor necrosis factor-alpha activity was associated with small-for-gestational-age birth, p = 0.028. With a threshold of 10 pg/ml, elevated amniotic fluid tumor necrosis factor-alpha had a sensitivity of 48% for the detection of small-for-gestational-age birth, with a specificity of 83%.
Conclusion: Elevated tumor necrosis factor-alpha in midtrimester amniotic fluid is associated with impaired intrauterine fetal growth. Abnormal immune system activation, as manifested by increased amniotic fluid tumor necrosis factor-alpha activity, may mediate impaired fetal growth in some cases.