Implantation and pregnancy rates in relation to oestradiol and progesterone profiles in cycles with and without the use of gonadotrophin-releasing hormone agonist suppression

The oestradiol (E₂), progesterone (P₄) levels, the corresponding E₂/P₄ ratios and pregnancy and implantation rates were studied in 565 in-vitro fertilization (IVF) cycles stimulated with gonadotrophins alone and in 320 cycles stimulated with adjunctive treatment of a gonadotrophin-releasing hormone agonist (GnRHa, leuprolide). The overall pattern of serum E₂ and P₄ levels and the E₂/P₄ ratios were similar in both groups, though significantly higher absolute levels were demonstrated in leuprolide cycles. Similar profiles were observed in conception and nonconception cycles within each group; significantly higher levels were noted in conception cycles starting nine days after embryo transfer. Though the overall pregnancy rate per fresh transfer in leuprolide cycles was significantly higher than in non-leuprolide cycles (32 versus 22%, P < 0.001), this was largely due to the transfer of more embryos; the implantation rate per embryo transferred did not differ significantly between groups (11.8 versus 10.5%). We conclude that the use of GnRHa in IVF cycles increases the pregnancy rate as a consequence of more embryos being transferred, since implantation rate was unaltered by GnRHa. Further, GnRHa does not alter the basic E₂ and P₄ progesterone pattern observed in gonadotrophin-stimulated cycles (though the absolute levels are higher); moreover, these patterns could not be used to predict pregnancy outcome.