['To compare levels of beta2-glycoprotein I antibodies with six different antiphospholipid antibodies (aPL) in sera from patients with certain adverse pregnancy conditions.', 'aPL levels were examined in pregnant women with anti-phospholipid syndrome (26), pre-eclampsia (32), autoimmune disease (12), or diabetes mellitus (23) and in a group with physiological pregnancy (38). A commercial ELISA was used to determine the serum levels of anti-beta2-GPI (Immunotech) in isotypes IgG and IgA, and anti-cardiolipin levels (Milenia) in IgG and IgM. aPL screening also included L-alpha-phosphatidic acid, L-alpha-phosphatidylethanolamine, L-alpha-phosphatidyl-DL-glycerol, L-alpha-phosphatidylinositol, and L-alpha-phosphatidyl-serine (Sigma, U.S.A.) in IgG and IgM. Statistical analysis of all aPL levels was made by cut-off levels for Ig isotypes by using 3 SD or 95th percentile calculated using STATGRAPHICS.', 'Positive levels of antibodies against beta2-GPI in IgA are more frequently associated with a diagnosis of anti-phospholipid syndrome, pre-eclampsia, and autoimmune disease in pregnant women than with diabetes mellitus in pregnancy. Very high interindividual differences in aPLs (against inositol, L-serine, cardiolipin, and beta2-glycoprotein in IgG and IgA) were found in serum from women with pregnancy complicated by anti-phospholipid syndrome, pre-eclampsia, and autoimmune disease. Pregnant patients with diabetes mellitus had higher serum levels in aPLs to DL-glycerol, inositol, L-serine, and beta2-glycoprotein. Positive aPL levels predominate in isotype IgG. Very low levels of aPLs to phosphatidic acid and phosphatidyl-ethanolamine were detected in all groups studied.'] Is beta 2-glycoprotein I a good indicator of certain adverse pregnancy conditions?