Principles and Practice of Controlled Ovarian Stimulation in ART 1st ed.

22. Luteal Support: What to Use When?

Sandeep Talwar 

(1)

Department of Obstetrics and Gynaecology, Nova IVI Fertility Clinics, New Delhi, Delhi, India

Sandeep Talwar

Email: sonutalwar2001@yahoo.co.in

Abstract

Supraphysiological hormonal profiles are the cause of luteal defect observed in stimulated IVF cycles. Hence it is essential to support the luteal phase in stimulated cycles for which different forms of support are available. Progesterone and human chorionic gonadotropins (hCGs) so far have been the ideal supports for pregnancy. HCG results in higher incidence of ovarian hyperstimulation. Luteal phase support with progesterone results in increase in implantation and pregnancy rates. For now, progesterone seems to be the best option as luteal phase support. Oral progesterone is associated with reduced bioavailablity. Vaginal progesterone is associated with increased at-site concentration.

Keywords

Luteal phaseProgesteronehCGLuteal support

22.1 Introduction

The menstrual cycle starts with rise in level of FSH (follicle-stimulating hormone). Rise of FSH co-relates with the rise of oestrogen. Simultaneously there is first recruitment of follicles and then selection of the dominant follicle. In the middle of menstrual phase there is rise of LH (leutinizing hormone). This rise of LH causes ovulation. After ovulation the dominant follicle gets transformed into a corpus luteum. Corpus luteum secretes progesterone and oestrogen of which progesterone is the dominant hormone.

If conception takes place, then developing blastocyst secretes hCG (human chorionic gonadotropin). The role of hCG is to maintain the corpus luteum and support it. If conception does not take place, then corpus luteum regresses and the level of progesterone and oestrogen falls, which is then followed by onset of menstruation.

The luteal phase forms a bridge between the ovulatory phase and the beginning of the menstrual cycle.

Along with the hormonal changes there are changes in the endometrium, which starts growing after menstruation under the influence of rise of oestrogen. After ovulation, there is rise of progesterone, which transforms it into a secretory endometrium. Progesterone prepares the endometrium for pregnancy by stimulating proliferation in response to hCG, which is produced by the corpus luteum. This occurs in the luteal phase of the menstrual cycle. Progesterone also promotes local vasodilatation and uterine musculature quiescence by inducing nitric oxide synthesis in the decidua.

The length of the luteal phase varies, the average being 14 days. Corpus luteum and the hormones secreted by it support the ongoing pregnancy initially for 8–12 weeks. This function is then taken over by the placenta.

22.2 Effect of Luteal-Phase Support on Endometrial microRNA Expression Following Controlled Ovarian Stimulation

It has been suggested that during ovarian stimulation for IVF, the endometrium becomes receptive after oocyte retrieval. Prior to and during the implantation process, the expression of multiple endometrial genes and gene products is highly regulated. The role of mRNAs in regulating cellular processes during the endometrial transition has recently attracted a great deal of attention. Neo-angiogenesis is a pivotal process in reproductive function where it regulates endometrial regeneration, corpus luteum formation and finally placentation. The regulatory function of mRNAs in the process of neo-angiogenesis has been illustrated in several in vitro and in vivo models.

The array-based study has revealed that there is an expression of a unique set of mRNAs in the endometrium following controlled ovarian stimulation. The level of expression for these mRNAs undergoes significant changes during the peri-implantation period. This expression is influenced by ovarian steroids. Expression of mRNAs may be associated with target genes and gene pathways. The mRNAs found to have enriched or depleted transcript load during the luteal phase may have specific roles in the control of endometrial receptivity during the peri-implantation period through regulation of their target genes [1].

22.3 Aetiology of Luteal Phase Defect (LPD) in ART Cycles

Removal of large quantities of granulosa cells during oocyte retrieval leads to diminished production of progesterone by corpora lutea, resulting in defect in the luteal phase. HCG administration for final oocyte maturation in stimulated IVF cycle could cause LPD by suppressing LH production via short-loop feedback mechanism [2].

Supraphysiological levels of steroids secreted by number of corpora lutea directly inhibit LH release via negative feedback actions at the hypothalamo-pituitary level. Corpus luteum requires consistent LH stimulus to perform its physiological function. LH support during luteal phase is responsible for maintenance and normal steroidogenic activity of the corpus luteum. As a result, unnecessary withdrawal of LH causes premature luteolysis [34]. LPD is also seen equally in stimulated cycles with use of GnRh antagonists [5]. Luteal phase support is thus an integral part of ART cycles.

22.4 Option for Luteal Support

Luteal support may be given as

1.

2.

3.

4.

22.4.1 Progesterone

Progesterone is a naturally occurring hormone secreted by the corpus luteum. In the presence of oestrogen, it transforms a proliferative endometrium into a secretory endometrium for implantation of the embryo. Progesterone also promotes local vasodilatation and uterine musculature quiescence by inducing nitric oxide synthesis in the decidua [6]. Once the embryo is implanted it acts to maintain the pregnancy.

22.4.1.1 Route of Administration

Oral Ingestion

Oral progesterone is extensively metabolized and has systemic side effects. There is reduced bioavailability. Micronized progesterone formulations initially used orally are now used vaginally [7]. Dehydrogesterone (DG), an oral progesterone, is a retroprogesterone with good oral bioavailability. According to Chakravarty et al., comparing oral DG vs. vaginal micronized progesterone for luteal support, both are associated with similar rates of successful pregnancies [8].

Intramuscular Injection

It is the most reliable route to achieve desired concentration of progesterone. It is rapidly absorbed, and peak level is reached in 8 h. Serum progesterone levels remain sustained compared to other routes as it is administered in an oil vehicle. It has the disadvantage of inconvenience of daily injections and pain or abscess formation at injection site. Allergic reactions may be seen. However, results are similar with intramuscular and vaginal progesterone.

The doses of IM progesterone used for LPS vary between 50 and 100 mg/day without any significant difference concerning the outcome [9]. Despite the conclusion of Pritts and Atwood's meta-analysis, vaginal administration of progesterone is a viable alternative to the IM injections of progesterone, as parenteral administration is associated with a high number of side effects [9]. On the basis of presented evidence, IM progesterone is not recommended as a first-choice LPS method in stimulated IVF cycles.

Rectal Administration

This route of progesterone administration is not widely accepted; there are minimal clinical trials on this method.

Vaginal Administration

Advantages of vaginal progesterone are patient comfort and effectiveness; there is high at-site concentration with low serum concentration. It does not cause drowsiness or sleepiness but is inconvenient because of vaginal discharge. Following intravaginal administration of progesterone, high uterine progesterone concentrations with low peripheral serum values are observed, due to counter-current exchange in progesterone transport between anatomically close blood vessels [10] and due to the uterine first-pass effect, where liver metabolization is absent [11]. It is a standard choice for luteal support. Vaginal and intramuscular progesterone have similar efficacy with comparable implantation and clinical pregnancy rates [12].

Vaginal delivery options are

·               Vaginal pessaries can be given in t.d.s or b.d dose. Patients have to lie flat for 30 min following insertion. Pessaries are messy and are associated with vaginal discharge. Occasionally the insertion can be associated with vaginal itching and perineal irritation.

·               Progesterone gel administration is delivered comfortably. There is no need to lie flat after insertion. The dose is 90 mg daily or B.D.

22.4.2 hCG

hCG is an indirect form of luteal support which acts by stimulating corpora lutea to produce progesterone. It is ineffective in the presence of inadequate number of LH receptors or a malfunctioning corpus luteum, which is hypo-responsive to hCG. hCG is effective if there is a specific defect in post-ovulatory LH secretion or in trophoblastic hCG production. It raises oestradiol and progesterone concentration, thus rescuing failing corpora lutea in stimulated IVF cycles. hCG administration increases concentration of placental protein [13], integrin and relaxin, which have been shown to increase at time of implantation [14]. The disadvantage of using hCG for luteal support stems from its potential for increasing rates of ovarian hyperstimulation syndrome (OHSS) when compared with other treatments or no treatment at all. With regard to OHSS, one should therefore be cautious with the administration of hCG for luteal supplementation in stimulated IVF cycles [13].

Luteal support with hCG should be avoided if E2 levels are >2,500–2,700 pg/ml on the day of hCG administration [15], or if the number of follicles is >10 [16]. According to the 2011 Cochrane database systematic review [17], luteal phase support with hCG provided significant benefit as compared to placebo or no treatment in terms of increased pregnancy rates and decreased miscarriage rates, but only when GnRha were used.

22.4.3 Oestradiol

The quality of endometrium on which implantation depends is affected by both progesterone and oestradiol. The role of progesterone for luteal support in stimulated cycles is clear. The role of oestradiol is not clear. There is a drop in oestrogen concentration in the luteal phase. There are some patients who could benefit from oestrogen addition during progesterone support. According to a meta-analysis by Kolibianakis et al. [18], the difference in pregnancy rates between two regimens, i.e. progesterone only and progesterone plus oestrogen, is very small.

According to a recent meta-analysis of 10 randomized controlled trials, 7 on GnRha and 3 on GnRh antagonists, the addition of oestrogen to progesterone for luteal phase support does not improve IVF outcomes [19].

|A study conducted and approved by the Johns Hopkins Hospital Institutional Review Board to evaluate the expression of miRNAs during the luteal phase following controlled ovarian stimulation for IVF and the influence of different luteal phase support protocols on miRNA profiles showed that after luteal phase support the miRNAs are up-regulated or down-regulated. Hence, luteal support following controlled ovarian stimulation has a profound influence on miRNA profiles. Up- or down-regulation of miRNAs after progesterone, or progesterone and oestrogen, suggests a role for luteal support in the peri-implantation uterus in IVF cycles through the regulation of associated target genes [20].

22.4.4 GnRh Agonist

GnRh agonist may support corpus luteum by stimulating secretion of LH by the pituitary, by acting on endometrium by locally expressed GnRh receptors, a direct effect on the embryos or by some combination of these possibilities. GnRh agonist also increased luteal phase hCG, E2 and progesterone in both stimulation regimens. It could be given as single dose or multiple dose.

22.4.4.1 Single Dose

The exact mechanism is still not known. It was suggested that GnRH-agonist can help in the maintenance of the corpus luteum, acting directly on the endometrium via local receptors, a direct effect on the embryos or by some combination of these possibilities. A single dose of GnRH agonist (0.5 mg leuprolide acetate) administered subcutaneously on day 6 after ICSI in both agonist and antagonist cycles enhanced pregnancy rates [21]. A meta-analysis showed that the luteal-phase single-dose GnRH-agonist administration can increase implantation rate in all cycles and clinical pregnancy rate and ongoing pregnancy rate in cycles with GnRH antagonist ovarian stimulation protocol [22]. GnRH agonist addition during the luteal phase significantly increases the probability of live birth rates [23].

22.4.4.2 Multiple Dose

In multiple-dose protocol, 200 μg intranasal buserelin followed by 100 μg every day or alternate day up to day 14 of the luteal phase is given. Intranasal administration of buserelin could be effective in triggering ovulation and in providing luteal support. This treatment was associated with a good pregnancy rate (28 %) with IUI [24].

22.5 Co-treatment Schemes

Besides support with progesterone, oestradiol and hCG co-treatment with ascorbic acid, aspirin, steroids or sildenafil is done to improve endometrial blood flow and receptivity.

22.5.1 Ascorbic Acid

Luteal regression is associated with ascorbate depletion and generation of reactive oxidative substances that inhibit LH action and block steroidogenesis. Griesinger conducted a prospective randomized study to evaluate impact of ascorbic acid as an addition to luteal support. They made the following observation: the addition of ascorbic acid provided no additional benefit in stimulated IVF cycles, regardless of dose used [25].

22.5.2 Steroids

There is a hypothesis that immunosuppression by exogenous steroids as a co-treatment for luteal phase support can be used to improve rates of embryo implantation and pregnancy. The rationale behind the use of steroids is that the embryos might be exposed to bacterial or leucocyte infiltration if the protective coating of zona pellucida is breached. In a prospective randomized control study involving routine ICSI patients, Ubaldi et al. did not find any beneficial effect of adding low-dose prednisolone to progesterone during the luteal phase [26].

22.5.3 Aspirin

Aspirin inhibits cyclooxygenase, thus avoiding prostaglandin synthesis. Luteal regression is caused by a pulsatile release of prostaglandins from the uterus in the late luteal phase [27]. Aspirin increases uterine blood flow; hence, it was postulated that it would increase endometrial receptivity, thereby increasing implantation [28]. Recent studies are unable to find benefit with routine use of aspirin during IVF cycles [29]. Aspirin may improve pregnancy rates in auto-antibody/sero-positive patients in repeated IVF failures [30].

22.5.4 Sildenafil

Sildenafil improves the uterine artery blood flow [31]. It acts as type 5 specific phosphodiesterase inhibitor by enhancing the vasodilatory effect of nitric oxide by preventing degradation of cyclic GMP. Sher et al. studied the effect of vaginal sildenafil on the outcome of in vitro fertilization (IVF) after multiple IVF failures attributed to poor endometrial development with a cohort of 105 infertile women aged less than 40 years, with normal ovarian reserve and at least two consecutive prior IVF failures attributed to inadequate endometrial development. Patients underwent IVF using long GnRha protocol with addition of sildenafil vaginal suppositories (25 mg, 4 times a day) for 3–10 days. Vaginal administration of sildenafil enhanced endometrial development in 70 % of patients studied. High implantation and ongoing pregnancy rates were achieved in a cohort with a poor prognosis for success [32].

22.6 Timing of Luteal Support

The timing of LPS should not be later than day 3 after OR. The hCG administered for final oocyte maturation covers the luteal phase for a maximum of 8 days. However, taking the uterolytic effect of progesterone into account, it is recommended to start treating the patients with progesterone at least as early as the day of embryo transfer [3334].

22.7 Duration of Luteal Support

Luteal support is continued until early pregnancy. There are no studies to either support or contest the generally accepted practice of prolonging progesterone supplementation during early pregnancy. Schmidt et al. (2001) were the first to publish a retrospective study to compare the delivery rate with IVF or ICSI in women who received progesterone supplementation with those who did not during the first weeks of pregnancy. The results showed no difference in the delivery rate [35].

Subsequently, a prospective randomized controlled trial was conducted by Nyobe et al. [36]. They evaluated whether or not the prolongation of luteal support during early pregnancy had any influence on the delivery rate after IVF. Results indicated that prolongation of progesterone supplementation in early pregnancy had no influence on the miscarriage rate, and thus no effect on the delivery rate. It would appear that the increase in endogenous hCG level during early pregnancy makes up for any possible lack of endogenous LH that has been caused by stimulated IVF cycles.

22.8 Results of the 2011 Cochrane Database Systematic Review Comparing Different Routes of Progesterone Supplementation [17]

Oral route is associated with reduction in pregnancy rates compared to intramuscular or vaginal but was not statistically significant. There is evidence of benefit of intramuscular over vaginal route in terms of outcome of ongoing pregnancy and live birth rate. There is no significant difference in pregnancy rate between vaginal progesterone gel and other types of vaginal progesterone. Luteal support with hCG provided significant benefit with increased pregnancy rates. There was no significant difference between progesterone and hCG or between progesterone and progesterone plus hCG or oestrogen in terms of pregnancy and miscarriage rates.

This review showed a significant effect in favour of progesterone for luteal phase support, favouring synthetic progesterone over micronized progesterone. Overall, the addition of other substances such as oestrogen or hCG did not seem to improve outcomes. There is no evidence favouring a specific route or duration of administration of progesterone. hCG, or hCG plus progesterone, was associated with a higher risk of OHSS. The use of hCG should therefore be avoided. There were significant results showing a benefit from addition of GnRH agonist to progesterone for the outcomes of live birth, clinical pregnancy and ongoing pregnancy. For now, progesterone seems to be the best option as luteal phase support, with better pregnancy results when synthetic progesterone is used.

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