THE ROLE OF PREGNANCY-SPECIFIC BETA-1 GLYCOPROTEIN (SP1) IN ASSESSINGHUMAN BLASTOCYST QUALITY IN-VITRO

The advent of new culture techniques resulting in more than 60% of emb ryos developing in vitro to the blastocyst stage suggests that blastoc yst transfer in humans with its potential to increase in-vitro fertili zation success rates could be a feasible option. Blastocyst quality ma rkers, however, are required to ensure that an increase in numbers is not achieved at the expense of lowering quality. We have previously re ported a morphology based method for grading blastocysts. The current study sought to determine whether the secretion of pregnancy-specific beta-1-glycoprotein (SP1) (a trophoblast product known to be associate d with fetal well-being) by blastocysts of differing quality was refle cted in the morphological grading. SP1 concentrations were measured in the culture medium of grade 1 (n = 19), grade 2 (n = 4) and grade 3 ( n = 4) blastocysts as well as vacuolated morulae (n = 6) daily from da y 1 to day 14. Cumulative SP1 concentrations secreted by blastocysts w ere significantly higher than those secreted by vacuolated morulae. Ho wever, SP1 levels could not distinguish between blastocysts of differi ng morphological grades. The inconsistent pattern of secretion suggest s that at this early stage of development, SP1 secretion is probably n ot sufficiently defined to allow any differences in levels to be refle cted by the morphological grading.