Pregnancy-specific beta 1 glycoprotein and chorionic gonadotrophin levels following conception.

Levels of pregnancy-specific beta 1 glycoprotein (SP1) and beta-subunit human chorionic gonadotropin (beta-hCG) were measured in the plasma of 22 subjects in early pregnancy following spontaneous or induced ovulation. Minimum baseline levels for pregnancy detection were set at 4 microgram/liter for SP1 an 15 IU/liter for beta-hCG. Using these levels, in some cases SP1 was detectable by day 17 following ovulation and beta-hCG by day 13. All patients were diagnosed as pregnant by day 20 using SP1 and by day 18 using beta-hCG. Both placental proteins had similar doubling times in the plasma. These was no difference between pregnancies following spontaneous and induced ovulation. Until accurate normal ranges can be obtained, there will be problems of interpretation of levels near the limits of the sensitivities of the assay in clinical situations.