Menotropin LH Content and Assisted Reproduction Outcome

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Summary

It has been suggested, that the outcome of assisted reproduction is deteriorated, when HMG is used for ovarian stimulation as compared to use of pure FSH preparations. Moreover, it has been assumed that this negative effect is caused by the content of LH in HMG. However, most prospective, randomized trials have shown equality of results between HMG and pure FSH, and a few even improved outcome with HMG as compared to pure FSH. Indeed, some recent data indicate, that the commonly used combination of pituitary down-regulation and recombinant human FSH, which is completely devoid of LH activity, results in such low levels of circulating LH, that the outcome of IVF is compromised. In a retrospective study we found, that half of normogonadotrophic women after GnRH agonist down-regulation combined with ovarian stimulation with recombinant FSH had mid-follicular levels of LH in serum below 0.5 IU/L. In this group of women a significantly increased risk of early pregnancy loss and a significantly lower chance of delivery was found when compared to the women with mid-follicular LH above 0.5 IU/L. Whether use of HMG or addition of exogenous LH to FSH stimulation protocols will improve the prognosis in these women remains to be proven in future prospective studies. 

Introduction

Although the first baby born after conception in vitro resulted from oocyte retrieval in a natural, unstimulated cycle, it was soon realised that increasing the number of mature oocytes by controlled ovarian hyper stimulation (COH) improved the success rates of IVF significantly. Up to the mid-eighties only human menopausal gonadotropins (HMG) containing equivalent FSH- and LH activity were available for COH. Using this stimulation method, however, the outcome of IVF was often jeopardised due to frequent occurrence of an untimely, spontaneous LH surge. In addition, some studies showed, that increased tonic levels of circulating LH during the follicular phase was associated with a poor reproductive outcome. During the 1980’s two measures were introduced in the IVF treatment to deal with these problems ascribed to harmful effects of LH:

i) use of GnRH agonist to suppress endogenous pituitary LH (and FSH) secretion, so-called down-regulation. 

ii) use of “pure” FSH preparations with reduced or virtually no content of LH. 

Pure FSH preparations were at the beginning like HMG derived from the urine of post menopausal women such as Metrodin and Metrodin HP (highly purified), Serono. During recent years, however, the recombinant human FSH preparations (Gonal-F Serono and Puregon Organon), which are devoid of any LH activity, have been introduced in COH. 

While stimulation protocols using GnRH agonist down-regulation undoubtedly have improved the success rates of IVF treatment, it can be questioned whether there is a genuine clinical benefit and cost-effectiveness in replacing of HMG with pure FSH for ovarian stimulation. 

Results and Discussion

A meta-analysis of clinical trials comparing HMG and urinary FSH in IVF has shown better results with FSH than with HMG, due to significantly fewer cases of complete failure of fertilization in the FSH group (Daya et al., 1995) Based on this study and more recent results from a larger prospective, randomized trial comparing HMG and FSH in GnRH agonist flare-up it was concluded, that the LH contained in HMG may be detrimental to the outcome of IVF, and that FSH should replace HMG in COH for IVF. This notion, however, has been challenged in a number of other prospective, randomized trials showing either equivalency between HMG and FSH or even an improved IVF-outcome with HMG as compared to urinary, highly purified FSH , due to a significantly higher fertilization rate and lower frequency of complete failure of fertilization in the HMG group (Westergaard et al., 1996). In contrast to the study of Daya et al. LH concentrations were monitored in this study and found significantly higher in the HMG group as compared to the FSH group. Therefore, these results contradict a harmful effect of the LH contained in HMG and indicate, that it may even be beneficial with regard to oocyte maturity and fertilizability. Moreover, recent studies have shown, that the combination of GnRH agonist down-regulation with urinary FSH-HP alone in a substantial subgroup of women results in such profound suppression of endogenous LH secretion (< 0.5 IU/L) during the mid-follicular phase, that oestradiol biosynthesis is significantly decreased and oocyte maturation and fertilisation capacity may be compromised, although the capacity of embryos to develop to the blastocyst stage in vitro seemed unaffected (Fleming et al., Hum.Reprod. 1998). 

In an attempt to further unravel the possible influence of profoundly depressed LH levels during ovarian stimulation for IVF, we conducted a retrospective study on 200 women, who were all normogonadotropic, and were treated with GnRH agonist down-regulation combined with recombinant FSH, which is completely devoid of LH activity. We found that 50% of these the women had mid-follicular serum concentrations of LH below 0.5 IU/L and the remainder above this level. With the exception of serum oestradiol concentration, which was significantly lower in the low LH group, all other parameters characterising the stimulation protocol, such as number of retrieved oocytes, fertilization rates and pregnancy rate per started cycle, were similar between the two groups. However, in the group of women with mid-follicular LH below 0.5 IU/L the frequency of early pregnancy loss was significantly higher than in the “normal” LH group; 45% versus 9%, p < 0.05 (Westergaard et al., 1999). These results indicate, that possible detrimental effects of profound suppression of endogenous LH may become manifest only after pregnancy is established. The explanation for this is unclear and needs further investigation in future prospective clinical studies.

Conclusion 

Available evidence from prospective randomized trials does not indicate a detrimental effect of the LH contained in HMG on the outcome of IVF. On the contrary, some recent data indicate, that the combination of GnRH agonist down-regulation and recombinant FSH in a substantial number of normogonadotropic women results in such low levels of circulating LH, that the outcome of IVF is compromised. Whether these women would benefit from treatment with HMG or recombinant FSH combined with recombinant LH remains to be proven in future prospective randomized trials.

References:

References

DAYA.S et al.: Randomized controlled trial of follicle stimulating hormone versus human menopausal gonadotrophin in in-vitro fertilization. Hum. Reprod., 10,n 392-396, 1995.

FLEMING R. et al.: Effects of profound suppression of luteinizing hormone during ovarian stimulation on follicular activity, oocyte and embryo function in cycles stimulated with purified follicle stimulating hormone. Hum. Reprod., 13, 1788-1792, 1998.

WESTERGAARD L. et al.: The effect of human menopausal gonadotrophin and highly purified, urine-derived follicle stimulating hormone on the outcome of in-vitro fertilization in down-regulated normogonadotrophic women. Hum. Reprod., 11, 1209-1213, 1996.

WESTERGAARD L. et al.: Low circulating levels of LH during ovarian stimulation affect the outcome of IVF negatively. In. Proceedings from the 11th World Congress on In Vitro Fertilization and Human Reproductive Genetics, Monduzzi Editore, Italy, pp. 279-282, 1999.2