Abstract: A disintegrin and metalloprotease 12 （ADAM12） with proteolytic activity is a placenta-
derived glycoprotein，which is involved in growth and differentiation. ADAM12-S can hydrolyze the insulin-like growth factor binding protein （IGFBP）. There is the secretory or soluble type of ADAM12 （ADAM12-S） in serum of pregnancy women，but there is not this type in non-pregnancy women. ADAM12-S levels tend to increase with the advanced gestational age in normal pregnancies. ADAM12 levels are correlated with maternal weight and ethnicity，but neither with maternal age. Smokers have lower ADAM12 levels than non-smokers. Serum ADAM12 level is highly stable. ADAM12 level is markedly decreased in the first trimester in pregnancies with foetal downs syndrome，but it is markedly elevated in the second trimester. ADAM12 levels are markedly decreased in the first trimester in pregnancies with trisomy 18，trisomy 13，Turner syndrome and triploidy. It is necessary to evaluate further the possibility that ADAM12 may be used as a additional or alternative marker in the first-trimester and second-trimester of pregnancy.

Key words: Pregnancy trimester, first, Pregnancy trimester, second, Aneuploid, Syndrome, Integrins, Metalloproteases