Recovery of luteal function after interruption of gonadotrophin secretion in the mid-luteal phase of the menstrual cycle

Novel Concepts for Inducing Final Oocyte Maturation in In Vitro Fertilization Treatment

Infertility affects one in six of the population and increasingly couples require treatment with assisted reproductive techniques. In vitro fertilization (IVF) treatment is most commonly conducted using exogenous FSH to induce follicular growth and human chorionic gonadotropin (hCG) to induce final oocyte maturation. However, hCG may cause the potentially life-threatening iatrogenic complication "ovarian hyperstimulation syndrome" (OHSS), which can cause considerable morbidity and, rarely, even mortality in otherwise healthy women. The use of GnRH agonists (GnRHas) has been pioneered during the last two decades to provide a safer option to induce final oocyte maturation. More recently, the neuropeptide kisspeptin, a hypothalamic regulator of GnRH release, has been investigated as a novel inductor of oocyte maturation. The hormonal stimulus used to induce oocyte maturation has a major impact on the success (retrieval of oocytes and chance of implantation) and safety (risk of OHSS) of IVF treatment. This review aims to appraise experimental and clinical data of hormonal approaches used to induce final oocyte maturation by hCG, GnRHa, both GnRHa and hCG administered in combination, recombinant LH, or kisspeptin. We also examine evidence for the timing of administration of the inductor of final oocyte maturation in relationship to parameters of follicular growth and the subsequent interval to oocyte retrieval. In summary, we review data on the efficacy and safety of the major hormonal approaches used to induce final oocyte maturation in clinical practice, as well as some novel approaches that may offer fresh alternatives in future.

Ovarian stimulation for IVF and endometrial receptivity--the missing link

The contemporary approach to ovarian stimulation for IVF treatment results in supraphysiological concentrations of steroids during the follicular and luteal phases of the menstrual cycle. These sex steroids act directly and indirectly to mature the endometrium, influencing receptivity for implantation. Corpus luteum function is distinctly abnormal in IVF cycles, and therefore luteal support is widely used. Various reasons may underlie the defective luteal phase, including (i) ovarian hyperstimulation per se, (ii) gonadotrophin-releasing hormone (GnRH) analogue co-treatment and (iii) the use of human chorionic gonadotrophin (HCG) to induce final oocyte maturation. The recent introduction of GnRH antagonist co-treatment for the prevention of a premature LH rise during the late follicular phase allows for different approaches to ovarian stimulation for IVF. However, a recent meta-analysis showed that implantation rates may be compromised by using GnRH antagonists in currently employed regimens. The development of endometrium receptive to embryo implantation is a complex process and may be altered by inappropriate exposure to sex steroids in terms of timing, duration and magnitude. New approaches to the assessment of endometrial receptivity are now required. Novel approaches to ovarian stimulation aimed at adjusted GnRH antagonist regimens and achieving a more physiological luteal phase endocrinology are now appearing in the literature and may represent an important step in the improvement of the overall health economics of IVF.

Induction of ovulation with pulsatile GnRH

The use of pulsatile GnRH to treat infertile women who do not ovulate has been shown to be safe, simple, and effective and the preferred method of inducing ovulation in appropriately selected patients who are resistant to treatment with clomiphene citrate. Treatment with GnRH is particularly effective for restoring ovulation in patients with idiopathic hypogonadotrophic hypogonadism and partially recovered weight-related amenorrhoea, but less successful in patients with polycystic ovary syndrome and organic hypothalamic pituitary disease. Based on personal experience, we advocate routine use of the subcutaneous route, using 15 micrograms per pulse every 90 min, and we monitor the patient's progress by serial ultrasound scanning and measurement of serum gonadotrophin and oestradiol concentrations. If the patient does not respond we recommend adding treatment with clomiphene citrate (Homburg et al, 1988b). Treatment with intravenous GnRH is reserved for women who do not respond to the above combination of drugs. We do not treat patients with GnRH until their body mass index is in the normal range (between 20-25) and we avoid GnRH treatment in patients with hypersecretion of LH during the follicular phase. If LH concentrations are raised, an alternative method of treatment is recommended, such as ovarian diathermy (Armar et al, 1990). Finally, the question of whether GnRH deficiency in patients with hypogonadotrophic hypogonadism is caused by a specific genetic lesion is not yet fully resolved. Yang-Feng et al (1986) used a cDNA clone encoding the human GnRH precursor molecule in order to assign the GnRH gene to a particular human chromosome. They found a single site for GnRH sequences in the human genome and that the gene coding for GnRH is located on the short arm of chromosome 8. Experiments in the congenitally hypogonadal mouse have shown that it is possible to restore gonadal development and gametogenesis by gene transfer (Mason et al, 1987). Clearly an abnormality at the level of the genome may be responsible for the secretory defect in patients with hypogonadotrophic hypogonadism, but it has yet to be defined (Weiss et al, 1989). Presumably elucidation awaits the development of more refined methods because both the genetics and the clinical associations of GnRH deficiency are most persuasive. Meanwhile replacement treatment with GnRH provides a simple and safe form of treatment for managing the clinical syndromes of GnRH deficiency.

Common problems in induction of ovulation

There are many groups of women with anovulatory infertility who respond abnormally to conventional treatment. It is important to diagnose the underlying disorder correctly before commencing treatment. In this chapter we have discussed the various treatment modalities available and how they may be adapted to fit the particular clinical needs. In women who are profoundly hypo-oestrogenic, the 'priming' of the ovary using prolonged low-dose gonadotrophins offers a possible solution if both subcutaneous and intravenous pulsatile GnRH therapy has failed. It may also reduce the incidence of multiple pregnancies in these women. Growth hormone seems to augment the response to gonadotrophin in these women and may prove a useful adjunct to therapy once further experience of its use has been reported. Women with PCO have been a difficult group to treat because of their tendency to hyperstimulate. The low-dose gonadotrophin regimen outlined in this chapter overcomes the majority of these problems without reducing the rate of conception. This group continue to have an increased incidence of miscarriage. The introduction of combined therapy of hMG with a GnRH analogue may improve this situation, but the data from randomized controlled studies are still awaited. Ovarian failure remains an untreatable cause of infertility. A few women may become pregnant spontaneously, but these are the exception rather than the rule. Hormone replacement therapy should be offered to all these women because of the long-term problems of osteoporosis and cardiovascular disease. Products containing a low dose of oestrogen (e.g. Premarin 0.625 mg) will not interfere with ovulation if there should be a spontaneous resumption of ovarian activity.

Regulation of steroid hormone synthesis by human corpora lutea: failure of follicle-stimulating hormone to support steroidogenesis in vivo and in vitro

The authors studied the role of follicle-stimulating hormone (FSH) in luteal steroidogenesis by replacing gonadotropin-releasing hormone (GnRH) infusion with pure FSH 48 hours after ovulation in two hypogonadotropic patients. Plasma progesterone (P) and estradiol (E2) decreased after FSH administration. Human luteal cells were cultured for 48 hours in the presence and absence of FSH, human chorionic gonadotropin (hCG), testosterone (T), or dibutyryl cyclic adenosine monophosphate (Bu2cAMP). In the presence of T, E2 synthesis increased significantly, indicating an active aromatase system in these cells. Human chorionic gonadotropin as well as Bu2cAMP significantly increased E2, T, and P synthesis. Follicle-stimulating hormone did not stimulate luteal E2, T, or P synthesis. The authors conclude that FSH does not sustain luteal steroidogenesis. Moreover, the in vitro findings reveal that hCG modulation of luteal E2 synthesis is mediated principally by an increase in androgen precursors. These in vivo and in vitro results confirm a crucial role for luteinizing hormone (LH) in the maintenance of luteal steroidogenesis.

One hundred pregnancies after treatment with pulsatile luteinising hormone releasing hormone to induce ovulation

OBJECTIVE

To review treatment with pulsatile luteinising hormone releasing hormone in infertile women who do not ovulate and are resistant to clomiphene after 100 pregnancies achieved with this treatment.

DESIGN

Retrospective analysis of 146 courses of treatment over 434 cycles.

SETTING

Infertility clinic.

PATIENTS

118 Women whose failure to ovulate was due to idiopathic hypogonadotrophic hypogonadism (n = 39), amenorrhoea related to low weight (n = 17), organic pituitary disease (n = 15), or polycystic ovaries (n = 47).

INTERVENTIONS

Dose of 15 micrograms luteinising hormone releasing hormone/pulse subcutaneously every 90 minutes given with a miniaturised pump throughout cycle monitored by ultrasound. Women with hypogonadotrophic hypogonadism had 48 courses, women with amenorrhoea related to low weight 23, women with organic pituitary disease 18, and women with polycystic ovaries 57.

END POINT

Follow up of 100 pregnancies achieved in 77 women during six years after introducing treatment. MEASUREMENTS and main results--One hundred pregnancies (seven multiple, 28 miscarriages). Cumulative rates of pregnancy were 93-100% at six months in women with idiopathic hypogonadotrophic hypogonadism, amenorrhoea related to low weight, and organic pituitary disease. In women with polycystic ovaries (cumulative rate of pregnancy 74%) adverse prognostic factors were obesity, hyperandrogenism, and high luteinising hormone concentrations, which were also associated with a high rate of early pregnancy loss.

CONCLUSIONS

Treatment with pulsatile luteinising hormone releasing hormone is safe, simple, and effective, and the preferred method of inducing ovulation in appropriately selected patients. Compared with exogenous gonadotrophin treatment there is little need for monitoring, no danger of hyperstimulation, and a low rate of multiple pregnancies.

Reduced frequency of luteinizing hormone pulses in women with weight loss-related amenorrhoea and multifollicular ovaries

We have studied pulsatile secretion of LH in 10 women with secondary amenorrhoea and multifollicular ovaries (MFO). This group of patients have a history of mild to moderate, or partially recovered weight loss. They have normal basal LH concentrations but evidence of oestrogen deficiency suggesting a hypothalamic abnormality of gonadotrophin regulation. The results of gonadotrophin pulse analysis were compared with those in normal women during the early follicular phase of the cycle. The mean LH concentration during the 8 h study (5.0 +/- 0.9 [SD] U/l) was not significantly different from that in normal women (5.7 +/- 2.5). There was no difference between the groups in mean LH pulse amplitude (2.1 +/- 0.5 in MFO; 2.2 +/- 1.3 in normal women). The frequency of LH pulses was, however, significantly lower in women with MFO (2.8 +/- 1.6 vs 4.8 +/- 1.5, P less than 0.05). Two women with MFO had LH pulses of normal frequency. One subsequently developed a normal pattern of ovarian follicles. The other showed a sleep-related rise in LH concentrations during a 24 h profile which was similar to the pattern of gonadotrophin secretion normally observed during late puberty. These results show that women with MFO have a hypothalamic disturbance of gonadotrophin regulation with slowing of LH pulses without a diminution of pulse amplitude.

Pulsatile infusion of gonadotrophin releasing hormone (GnRH): investigative and therapeutic applications

Normal gonadotrophin secretion, and therefore normal ovarian function, depend on delivery to the pituitary of the hypothalamic neuropeptide gonadotrophin releasing hormone (GnRH) in a pulsatile pattern. In the mid-follicular phase of the menstrual cycle, for example, discrete pulses of luteinizing hormone (LH) can be observed at approximately 90 min intervals. Many disorders of ovulation are caused by abnormalities of this natural pulsed signal. We have developed and used a small portable infusion pump to deliver GnRH to women with hypothalamic amenorrhoea; our studies, and those of other groups, have shown that successful ovulation and pregnancy result from such treatment. The results of treatment at St Mary's Hospital show that 16 women with hypogonadotrophic amenorrhoea received a total of 31 cycles of treatment with pulsatile GnRH; 25 (81%) of these cycles were ovulatory and 11 of the 14 women who were trying to conceive became pregnant. There was only one multiple pregnancy (twins).