Early hCG addition to rFSH for ovarian stimulation in IVF provides better results and the cDNA copies of the hCG receptor may be an indicator of successful stimulation

The achievement of a simple, safe and cost-effective treatment protocol in controlled ovarian hyperstimulation (COH) is of paramount importance to improve the quality of care in assisted reproduction. It is particularly important in the case of previous unsuccessful attempts. The midcycle gonadotrophin surge is a major event in the dynamics of ovulation. Rapidly increasing levels of luteinising hormone (LH) induce a number of key changes in both oocytes and follicular cells, which further modify the steroid and protein micro- and macroenvironment. These physiologic changes have a prominent role in the normal maturation of oocytes, the process of ovulation, and in subsequent fertilization and implantation [1].Human chorionic gonadotrophin (hCG) has been used as a substitute for the LH surge because of the degree of homology between the two hormones [2]. hCG has a slower plasma metabolic clearance, which consists of a rapid phase in the first 5-9 h following intramuscular (IM) administration and a slower phase in the first 1-1.3 days after administration. Both LH and hCG are complex heterodimeric glycoproteins with a molecular weight of ~30 K for recombinant human LH (rLH) and 40 K for hCG. Their carbohydrate molecule is, though, different, thus leading possibly to a different affinity to the LH/hCG receptor and therefore to a differentiated function between LH and hCG. These two hormones have identical α-subunits and a high cysteine content. Most importantly, they have the same natural function--to cause ovulation and support lutein cells. The major differences between the two hormones include the sequence of the β-subunit, the regulation of the secretion of the two hormones, the carbohydrate component and the pharmacokinetics of clearance of hCG as opposed to LH [3,4].The LH/hCG receptor has an almost ubiquitous distribution in reproductive organs, thus suggesting that the actions of hCG might be more extensive than previously thought. Independently of follicular st