The optimum time for exogenous human chorionic gonadotropin to rescue the corpus luteum

Investigation of luteal HCG supplementation in GnRH-agonist-triggered fresh embryo transfer cycles: a randomized controlled trial

RESEARCH QUESTION

Does splitting the human chorionic gonadotrophin (HCG) support in IVF cycles triggered by a gonadotrophin-releasing hormone agonist result in a better progesterone profile?

DESIGN

Randomized controlled three-arm study, performed at the Fertility Clinic, Odense University Hospital, Denmark. Patients with 12-25 follicles ≥12 mm were randomized into three groups: Group 1 - ovulation triggered with 6500 IU HCG; Group 2 - ovulation triggered with 0.5 mg GnRH agonist, followed by 1500 IU HCG on the day of oocyte retrieval (OCR); and Group 3 - ovulation triggered with 0.5 mg GnRH agonist, followed by 1000 IU HCG on the day of OCR and 500 IU HCG on OCR + 5. All groups received 180 mg vaginal progesterone. Progesterone concentrations were analysed in eight blood samples from each patient.

RESULTS

Sixty-nine patients completed the study. Baseline and laboratory data were comparable. Progesterone concentration peaked on OCR + 4 in Groups 1 and 2, and peaked on OCR + 6 in Group 3. On OCR + 6, the progesterone concentration in Group 2 was significantly lower compared with Groups 1 and 3 (P = 0.003 and P < 0.001, respectively). On OCR + 8, the progesterone concentration in Group 3 was significantly higher compared with the other groups (both P<0.001). Progesterone concentrations were significantly higher in Group 3 from OCR + 6 until OCR + 14 compared with the other groups (all P ≤ 0.003). Four patients developed ovarian hyperstimulation syndrome in Group 3.

CONCLUSION

Sequential HCG support after a GnRH agonist trigger provides a better progesterone concentration in the luteal phase.

Evaluation of endometrial receptivity and implantation failure

PURPOSE OF REVIEW

To succinctly review the basic mechanisms of implantation and luteal phase endometrial differentiation, the etiologies of impaired endometrial function and receptivity, and the current methods that exist to evaluate and treat impaired endometrial receptivity.

RECENT FINDINGS

Human embryo implantation requires bidirectional communication between blastocyst and a receptive endometrium. Etiologies of impaired endometrial receptivity are varied. Some of these include delayed endometrial maturation, structural abnormalities, inflammation, and progesterone resistance. Current methods to evaluate endometrial receptivity include ultrasonography, hysteroscopy, and endometrial biopsy. Treatments are limited, but include operative hysteroscopy, treatment of endometriosis, and personalized timing of embryo transfer.

SUMMARY

Although some mechanisms of impaired endometrial receptivity are well understood, treatment options remain limited. Future efforts should be directed towards developing interventions targeted towards the known mediators of impaired endometrial receptivity.

Local and systemic factors and implantation: what is the evidence?

Significant progress has been made in the understanding of embryonic competence and endometrial receptivity since the inception of assisted reproductive technology. The endometrium is a highly dynamic tissue that plays a crucial role in the establishment and maintenance of normal pregnancy. In response to steroid sex hormones, the endometrium undergoes marked changes during the menstrual cycle that are critical for acceptance of the nascent embryo. There is also a wide body of literature on systemic factors that impact assisted reproductive technology outcomes. Patient prognosis is impacted by an array of factors that tip the scales in her favor or against success. Recognizing the local and systemic factors will allow clinicians to better understand and optimize the maternal environment at the time of implantation. This review will address the current literature on endometrial and systemic factors related to impaired implantation and highlight recent advances in this area of reproductive medicine.

Endometrial development and function in experimentally induced luteal phase deficiency

CONTEXT

It is generally assumed that delayed endometrial development observed in luteal phase deficiency (LPD) is the result of abnormally low progesterone (P) levels. This hypothesis has never been tested by direct experiment.

OBJECTIVE

Our objective was to evaluate the effects of P concentrations on human endometrium.

DESIGN AND SETTING

A randomized trial was conducted at an academic medical center.

SUBJECTS

Twenty-nine healthy, ovulatory 18- to 35-yr-old women participated.

INTERVENTION

Endometrial samples were obtained from women in natural cycles and two groups of experimentally modeled cycles. Women undergoing modeled cycles were treated with GnRH agonist and a fixed physiological dose of transdermal estradiol, followed by randomization to 10 or 40 mg daily im P administration to achieve either normal circulating luteal P or 4-fold lower P concentrations, the latter representing an experimental model of LPD.

MAIN OUTCOME MEASURES

Tissue specimens, obtained after 10 days of P exposure, were analyzed by histological dating, immunohistochemistry, immunoblot, and real-time quantitative RT-PCR (qRT-PCR).

RESULTS

Histological dating of endometrium, immunohistochemistry for endometrial integrins, and qRT-PCR analysis for nine putative functional markers showed no differences between the three groups. Preliminary data from Western analysis suggest that some proteins may be affected by low serum P concentrations.

CONCLUSIONS

Histological endometrial dating does not reflect circulating P concentrations and cannot serve as a reliable bioassay of the quality of luteal function. Assessment of selected functional markers by either immunohistochemistry or qRT-PCR is similarly insensitive to decreased circulating P. Preliminary evidence suggests that abnormally low luteal phase serum P concentrations may have important functional consequences not otherwise detected.

Renal Hemodynamic Effects of Relaxin in Humans

Rat studies have convincingly demonstrated the essential role of the ovarian hormone relaxin in mediating gestational renal hemodynamic and osmoregulatory changes in that species. We describe a model in nonpregnant volunteers using exogenous hCG to stimulate the production and release of ovarian relaxin in order to assess renal hemodynamic responses. Women (n = 10) were serially studied +/- hCG stimulation during menstrual cycles with measurement of inulin, PAH, and neutral dextran clearances (to determine glomerular filtration rate [GFR], renal plasma flow [RPF], and glomerular porosity, respectively). Controls were women without ovarian function (n = 6) and men (n = 10). GFR and RPF were increased in the luteal phase compared to the follicular phase (15.3% increase in GFR, P < 0.005; 17.8% increase in RPF, P < 0.05). In controls, GFR and RPF were not significantly different between study occasions. Although exogenous hCG did not stimulate relaxin secretion in women without ovarian function or in men, it did so in normal women, but not into the pregnancy range. In no group were renal hemodynamics augmented by administered hCG. In naturally occurring cycles, increased serum relaxin is associated with augmented renal hemodynamics. As luteal stimulation with hCG failed to yield pregnancy relaxin levels, the use of exogenous relaxin for human administration is needed to further elucidate the renal vasodilatory properties of relaxin.

Rescue of the corpus luteum in human pregnancy

Rescue of the corpus luteum from its programmed senescence maintains progesterone production required for pregnancy. In primates, chorionic gonadotropin produced by the developing conceptus acts as the primary luteotrophic signal. The purpose of this research was to assess corpus luteum rescue by examining changes in daily urinary progesterone metabolite levels during the first week after implantation. We determined the variability in progesterone metabolite profiles and evaluated its relationship to early pregnancy loss in 120 naturally conceived human pregnancies, including 43 early pregnancy losses. In other primates, an abrupt increase in the progesterone metabolite occurs at the time of implantation. This pattern occurred in an estimated 45% of the pregnancies in the present study. In the remaining pregnancies, there was a delayed rise (18%), neither a rise or decline (22%), or a decline (15%) during the week after implantation. The estimated rate of early pregnancy loss increased across these categories (from 5% loss with an abrupt rise at implantation to 100% loss with progesterone metabolite decline). Low urinary hCG levels in early pregnancy were significant determinants of a decline in postimplantation progesterone metabolite. However, preimplantation steroid metabolite levels were not significant, suggesting no inherent problem with the corpus luteum. Examination of individual progesterone metabolite profiles in relation to hCG profiles also indicated that few losses were caused by corpus luteum failure. Delineating the functional importance of an abrupt progesterone rise at the time of implantation may provide new strategies for promoting successful implantation in assisted reproduction.

Corpus luteum response to exogenous HCG during the mid-luteal phase of the menstrual cycle

OBJECTIVE

To assess a range of exogenous HCG regimes designed to simulate the endocrine environment occurring in biochemical, single and multiple pregnancies and to study the response of the corpus luteum to those regimes.

DESIGN

Prospective clinical study.

PATIENTS

Twenty-five normally cycling women aged 24-35 years were given one of four regimes of HCG injections designed to mimic the HCG concentrations found following spontaneous implantation. Regimes A, B, C and D were designed with starting HCG doses of 60, 140, 250 and 1000 iu, respectively. The daily HCG injections were then increased to give a doubling concentration every 30 h for regime A, every 27 h for regime B, every 24 h for regimes C and D. HCG administration was started on either days 7 or 8 after the LH peak.

MEASUREMENTS

Plasma HCG and progesterone concentrations.

RESULTS

Subjects given regime A failed to demonstrate any rescue of the corpus luteum despite low-detectable amounts of HCG in the circulation equivalent to those seen in some biochemical pregnancies. In contrast, subjects given regimes B and C demonstrated prompt increases in progesterone secretion immediately after the first HCG injection achieving HCG and progesterone concentrations in plasma similar to those seen in normal singleton pregnancies. Subjects given regime D also showed rapid rescue of the corpus luteum but this time achieved plasma HCG concentrations in the range normally seen in multiple pregnancies. All subjects in regimes B, C and D secreted significantly higher amounts of progesterone than those in regime A (P<0.001). However, despite the greater amounts of HCG used in regime D, the amount of progesterone produced was not significantly different from regimes B or C.

CONCLUSIONS

The exogenous HCG regimes used in this study successfully mimicked the hormonal environment found in biochemical, single and multiple pregnancies and elicited appropriate corpus luteum responses.

A prospective, randomized, controlled, double-blind, double-dummy comparison of recombinant and urinary HCG for inducing oocyte maturation and follicular luteinization in ovarian stimulation

A randomized, controlled, double-blind, double-dummy, phase III clinical trial was conducted in 84 women to compare the efficacy of a s.c. injection of 250 microg recombinant human chorionic gonadotrophin (rHCG; Ovidrel) to an i.m. injection of 5000 IU urinary HCG (uHCG; Profasi) in inducing folliculogenesis, resumption of oocyte meiosis and luteinization after ovulation induction with recombinant follicle stimulating hormone (Gonal-F). The study primary endpoint was comparison of the number of oocytes retrieved per patient receiving either compound. Secondary comparisons included the number of oocytes retrieved per follicles aspirated; the number of mature oocytes; normally fertilized oocytes; and cleaved embryos. There were no statistically significant differences between groups for the primary endpoint (mean +/- SD oocytes retrieved 10.8 +/- 4.5 for rHCG versus 10.3 +/- 5.1 for uHCG) or each of the secondary endpoints except for increased concentrations of progesterone 6-7 days after rHCG administration (353.2 +/- 215.1 versus 234.1 +/- 129.4 nmol/l; P < 0. 004) and for HCG during the luteal phase following rHCG (P < 0.02). There were also no significant side-effects for either drug. Since the confidence intervals for the difference of the number of oocytes retrieved between the two treatment groups were within the bounds defined by the multi-trial protocol equivalence between rHCG and uHCG could be declared.