Identification of pregnancy from bloodstains by radioimmunoassay for pregnancy specific β1-glycoprotein (SP1)

Y. Yamamoto

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Pregnancy specific β1-glycoprotein (SP1), one of the pregnancy-specific proteins, has been detected by a radioimmunoassay, and its usefulness for the identification of pregnancy blood and bloodstains has been investigated. The lowest measurable concentration of SP1, obtained by a radioimmunoassay, was found to be about 4 ng/ml. SP1 was detected in pregnancy blood samples as early as the 5th week of pregnancy at a level of 0.945 μg/ml, and it reached on average 95.83 μg/ml in the 10th month after gradual increases. In testings of pregnancy bloodstain SP1 was 0.883 μg/ml at the 5th week of pregnancy, then gradually increased, and became 89.94 μg/ml on average in the 10th month of pregnancy. In blood or in bloodstain samples from subjects other than pregnant women, the umbilical cord blood of newborn babies had 0.08 μg/ml (mean) of SP1, and their umbilical cord bloodstains also contained trace amounts of SP1, while no SP1 was detected in blood or in the bloodstain samples from nonpregnant women, men and infants. SP1 in pregnant blood samples stored at room temperature remained stable for 2 weeks, but then it decreased relatively rapidly to 43.0% in 1 month, 7.1% in 2 months, and 2.6% in 3 months, of the original amount. In bloodstain samples stored at room temperature, SP1 remained relatively stable, and 55.0% of the pre-staining level was detected 6 months later, 47.5% after 1 year, and 27.0% 2 years later. SP1 in pregnant blood was relatively unstable to heat. Heating at 50°C for 30 min decreased SP1 to 59.8%, and at 60° for 30 min it decreased further to 1.2%. In pregnant bloodstains, SP1 proved fairly stable to heating for 30 min in a temperature range from 50°C to 120°C, and 74.6% remained even after heating at 150°C for 30 min. Identification of pregnancy bloodstains was attempted using our standard procedures and experimentally prepared bloodstains (5 mm in diameter) on cotton cloth stored at room temperature. As a result, SP1 was detected in all 201 pregnancy bloodstains tested, which had been prepared with blood samples collected from 2-10 month pregnant women and stored for 1 day-2 years, and the positivity was 100%. On the other hand, all bloodstains that had been prepared with blood samples from non-pregnant subjects showed negative results. Thus, pregnant bloodstains were distinguishable from non-pregnant bloodstains. These results indicate that the present method utilizing radioimmunoassay for SP1 is a highly specific and sensitive method for identifying pregnancy blood.

Original languageEnglish
Pages (from-to)279-293
Number of pages15
JournalJapanese Journal of Legal Medicine
Issue number4
Publication statusPublished - Jan 1 1987
Externally publishedYes

ASJC Scopus subject areas

  • Health Policy
  • Law


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