The predictive value of pregnancy-specific β1-glycoprotein (SP1) in threatened abortion

Pregnancy-specific β1-glycoprotein (SP1) was determined in the serum of 59 patients admitted to hospital with threatened abortion in the 7th–19th wk of pregnancy. A 95% reference area was calculated on the basis of values from patients with threatened abortion who continued pregnancy until delivery. 26 patients aborted; among these 24 showed values below the reference area. 33 continued pregnancy until confinement. 3 of these initially had values just under the lower limit of the reference area; later values from these patients as well as all the values from the remaining 30 patients were all above this limit. The value of a single low SP1 for prediction of abortion was found to be 89% (95% conf. lim.: 70.8–97.7). Based on serial determinations the predictive value was 100% (95% conf. lim.: 85.8–100.0).