Specific and sensitive determination of pregnancy-specific beta 1-glycoprotein by radioimmunoassay. A new pregnancy test.

A specific and highly sensitive radioimmunoassay (R.I.A.) for determination of pregnancy-specific beta 1-glycoprotein (S.P.1) in human plasma, urine, amniotic fluid, and breast milk has been developed. The minimum detection limit of S.P.1 was 8 mug/1 of sample. The assay was applied to plasma and/or urine samples from 8 women in early pregnancy. S.P. 1 was detected in the plasma of all three women obtained within 14 days of ovulation, the earliest positive result being at 7 days. In another woman plasma was negative at day 18 and positive by day 22. In the three remaining women plasma S.P.1 was detected when measured within 24 to 36 days of ovulation. S.P.1 was detected in four urine samples obtained between 20 and 28 days after ovulation. S.P.1 was also measured in breast milk, amniotic fluid, cord blood, and plasma of women with ectopic gestation and trophoblastic disease. It is suggested that the assay of S.P.1 may have important advantages over existing systems for detection and monitoring of early pregnancy.