Prevention of severe ovarian hyperstimulation syndrome (OHSS) in IVF patients by steroidal ovarian suppression--a prospective randomized study

TGF-β1 and TGF-β3, but not TGF-β2, are upregulated in the ovaries of ovarian hyperstimulation syndrome†

Ovarian hyperstimulation syndrome (OHSS) is a life-threatening and potentially fatal complication during in vitro fertilization treatment. The levels of transforming growth factor-β1 (TGF-β1) are upregulated in human follicular fluid and granulosa-lutein cells (hGL) of OHSS patients and could contribute to the development of OHSS by downregulating steroidogenic acute regulatory protein (StAR) expression. However, whether the same is true for the other two members of the TGF-β family, TGF-β2 and -β3, remains unknown. We showed that all three TGF-β isoforms were expressed in human follicular fluid. In comparison, TGF-β1 was expressed at the highest level, followed by TGF-β2 and TGF-β3. Compared to non-OHSS patients, follicular fluid levels of TGF-β1 and TGF-β3 were significantly upregulated in OHSS patients. The same results were observed in mRNA levels of TGF-β isoforms in hGL cells and ovaries of OHSS rats. In addition, StAR mRNA levels were upregulated in hGL cells of OHSS patients and the ovaries of OHSS rats. Treatment cells with TGF-β isoforms downregulated the StAR expression with a comparable effect. Moreover, activations of SMAD3 signaling were required for TGF-β isoforms-induced downregulation of StAR expression. This study indicates that follicular fluid TGF-β1 and TGF-β3 levels could be used as biomarkers and therapeutic targets for the OHSS.

Luteal phase support for assisted reproduction cycles

BACKGROUND

Progesterone prepares the endometrium for pregnancy by stimulating proliferation in response to human chorionic gonadotropin(hCG) produced by the corpus luteum. This occurs in the luteal phase of the menstrual cycle. In assisted reproduction techniques(ART), progesterone and/or hCG levels are low, so the luteal phase is supported with progesterone, hCG or gonadotropin-releasing hormone (GnRH) agonists to improve implantation and pregnancy rates.

OBJECTIVES

To determine the relative effectiveness and safety of methods of luteal phase support provided to subfertile women undergoing assisted reproduction.

SEARCH METHODS

We searched databases including the Cochrane Menstrual Disorders and Subfertility Group (MDSG) Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO and trial registers. We conducted searches in November 2014, and further searches on 4 August 2015.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of luteal phase support using progesterone, hCG or GnRH agonist supplementation in ART cycles.

DATA COLLECTION AND ANALYSIS

Three review authors independently selected trials, extracted data and assessed risk of bias. We calculated odds ratios (ORs) and 95%confidence intervals (CIs) for each comparison and combined data when appropriate using a fixed-effect model. Our primary out come was live birth or ongoing pregnancy. The overall quality of the evidence was assessed using GRADE methods.

MAIN RESULTS

Ninety-four women RCTs (26,198 women) were included. Most studies had unclear or high risk of bias in most domains. The main limitations in the evidence were poor reporting of study methods and imprecision due to small sample sizes.1. hCG vs placebo/no treatment (five RCTs, 746 women)There was no evidence of differences between groups in live birth or ongoing pregnancy (OR 1.67, 95% CI 0.90 to 3.12, three RCTs,527 women, I2 = 24%, very low-quality evidence, but I2 of 61% was found for the subgroup of ongoing pregnancy) with a random effects model. hCG increased the risk of ovarian hyperstimulation syndrome (OHSS) (1 RCT, OR 4.28, 95% CI 1.91 to 9.6, low quality evidence).2. Progesterone vs placebo/no treatment (eight RCTs, 875 women)Evidence suggests a higher rate of live birth or ongoing pregnancy in the progesterone group (OR 1.77, 95% CI 1.09 to 2.86, five RCTs, 642 women, I2 = 35%, very low-quality evidence). OHSS was not reported.3. Progesterone vs hCG regimens (16 RCTs, 2162 women)hCG regimens included comparisons of progesterone versus hCG and progesterone versus progesterone + hCG. No evidence showed differences between groups in live birth or ongoing pregnancy (OR 0.95, 95% CI 0.65 to 1.38, five RCTs, 833 women, I2 = 0%, low quality evidence) or in the risk of OHSS (four RCTs, 615 women, progesterone vs hCG OR 0.54, 95% CI 0.22 to 1.34; four RCTs,678 women; progesterone vs progesterone plus hCG, OR 0.34, 95% CI 0.09 to 1.26, low-quality evidence).4. Progesterone vs progesterone with oestrogen (16 RCTs, 2577 women)No evidence was found of differences between groups in live birth or ongoing pregnancy (OR 1.12, 95% CI 0.91 to 1.38, nine RCTs,1651 women, I2 = 0%, low-quality evidence) or OHSS (OR 0.56, 95% CI 0.2 to 1.63, two RCTs, 461 women, I2 = 0%, low-quality evidence).5. Progesterone vs progesterone + GnRH agonist (seven RCTs, 1708 women)Live birth or ongoing pregnancy rates were lower in the progesterone-only group and increased in women who received progester one and one or more GnRH agonist doses (OR 0.62, 95% CI 0.48 to 0.81, nine RCTs, 2861 women, I2 = 55%, random effects, low quality evidence). Statistical heterogeneity for this comparison was high because of unexplained variation in the effect size, but the direction of effect was consistent across studies. OHSS was reported in one study only (OR 1.00, 95% CI 0.33 to 3.01, 1 RCT, 300 women, very low quality evidence).6. Progesterone regimens (45 RCTs, 13,814 women)The included studies reported nine different comparisons between progesterone regimens. Findings for live birth or ongoing pregnancy were as follows: intramuscular (IM) versus oral: OR 0.71, 95% CI 0.14 to 3.66 (one RCT, 40 women, very low-quality evidence);IM versus vaginal/rectal: OR 1.24, 95% CI 1.03 to 1.5 (seven RCTs, 2309 women, I2 = 71%, very low-quality evidence); vaginal/rectal versus oral: OR 1.19, 95% CI 0.83 to 1.69 (four RCTs, 857 women, I2 = 32%, low-quality evidence); low-dose versus high-dose vaginal: OR 0.97, 95% CI 0.84 to 1.11 (five RCTs, 3720 women, I2 = 0%, moderate-quality evidence); short versus long protocol:OR 1.04, 95% CI 0.79 to 1.36 (five RCTs, 1205 women, I2 = 0%, low-quality evidence); micronised versus synthetic: OR 0.9, 95%CI 0.53 to 1.55 (two RCTs, 470 women, I2 = 0%, low-quality evidence); vaginal ring versus gel: OR 1.09, 95% CI 0.88 to 1.36 (oneRCT, 1271 women, low-quality evidence); subcutaneous versus vaginal gel: OR 0.92, 95% CI 0.74 to 1.14 (two RCTs, 1465 women,I2 = 0%, low-quality evidence); and vaginal versus rectal: OR 1.28, 95% CI 0.64 to 2.54 (one RCT, 147 women, very low-quality evidence). OHSS rates were reported for only two of these comparisons: IM versus oral, and low versus high-dose vaginal. No evidence showed a difference between groups.7. Progesterone and oestrogen regimens (two RCTs, 1195 women)The included studies compared two different oestrogen protocols. No evidence was found to suggest differences in live birth or ongoing pregnancy rates between a short and a long protocol (OR 1.08, 95% CI 0.81 to 1.43, one RCT, 910 women, low-quality evidence) or between a low dose and a high dose of oestrogen (OR 0.65, 95% CI 0.37 to 1.13, one RCT, 285 women, very low-quality evidence).Neither study reported OHSS.

AUTHORS' CONCLUSIONS

Both progesterone and hCG during the luteal phase are associated with higher rates of live birth or ongoing pregnancy than placebo.The addition of GnRHa to progesterone is associated with an improvement in pregnancy outcomes. OHSS rates are increased with hCG compared to placebo (only study only). The addition of oestrogen does not seem to improve outcomes. The route of progester one administration is not associated with an improvement in outcomes.

Co action of CFTR and AQP1 increases permeability of peritoneal epithelial cells on estrogen-induced ovarian hyper stimulation syndrome

Background

Ovarian hyper stimulation syndrome (OHSS) is an iatrogenic complication associated with fertility drugs. It is characterized by increased vascular permeability and substantial fluid shift with accumulation in the body cavity. The pathogenesis of OHSS remains obscure, and no definitive treatments are currently available.

Results

Using western blot and short-circuit current (Isc) techniques, we investigate the potential coactions of analysis in cystic fibrosis transmembrane conductance regulator (CFTR) and aquaporin 1 (AQP1) on the hyper permeability of body cavity peritoneal epithelial cells in the pathogenesis of OHSS. The rats develop OHSS symptoms, with the up regulation of both CFTR and AQP1 expression and enhanced CFTR channel activity in peritoneal epithelial cells, can also be mimicked by administration of estrogen, alone in ovariectomized rats. Administration of progesterone suppresses CFTR activity, OHSS symptoms as well as CFTR and AQP1 expression. Besides, AQP1 inhibitor, HgCl₂, can suppress CFTR channel activity. Therefore, antisera against CFTR or AQP1 to OHSS animals may result in alleviation of the symptom.

Conclusion

This study confirms the coactions of CFTR and AQP1 play a critical role in the development and progression of increased peritoneal epithelial permeability in severe OHSS. These findings may provide grounds for ameliorating assisted reproduction treatment strategy to reduce the risk of OHSS in in vitro fertilization (IVF).

Luteal phase support for assisted reproduction cycles

BACKGROUND

Progesterone prepares the endometrium for pregnancy by stimulating proliferation in response to human chorionic gonadotropin (hCG), which is produced by the corpus luteum. This occurs in the luteal phase of the menstrual cycle. In assisted reproduction techniques (ART) the progesterone or hCG levels, or both, are low and the natural process is insufficient, so the luteal phase is supported with either progesterone, hCG or gonadotropin releasing hormone (GnRH) agonists. Luteal phase support improves implantation rate and thus pregnancy rates but the ideal method is still unclear. This is an update of a Cochrane Review published in 2004 (Daya 2004).

OBJECTIVES

To determine the relative effectiveness and safety of methods of luteal phase support in subfertile women undergoing assisted reproductive technology.

SEARCH STRATEGY

We searched the Cochrane Menstrual Disorders and Subfertility Group (MDSG) Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO, CINAHL, Database of Abstracts of Reviews of Effects (DARE), LILACS, conference abstracts on the ISI Web of Knowledge, OpenSigle for grey literature from Europe, and ongoing clinical trials registered online. The final search was in February 2011.

SELECTION CRITERIA

Randomised controlled trials of luteal phase support in ART investigating progesterone, hCG or GnRH agonist supplementation in in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) cycles. Quasi-randomised trials and trials using frozen transfers or donor oocyte cycles were excluded.

DATA COLLECTION AND ANALYSIS

We extracted data per women and three review authors independently assessed risk of bias. We contacted the original authors when data were missing or the risk of bias was unclear. We entered all data in six different comparisons. We calculated the Peto odds ratio (Peto OR) for each comparison.

MAIN RESULTS

Sixty-nine studies with a total of 16,327 women were included. We assessed most of the studies as having an unclear risk of bias, which we interpreted as a high risk of bias. Because of the great number of different comparisons, the average number of included studies in a single comparison was only 1.5 for live birth and 6.1 for clinical pregnancy.Five studies (746 women) compared hCG versus placebo or no treatment. There was no evidence of a difference between hCG and placebo or no treatment except for ongoing pregnancy: Peto OR 1.75 (95% CI 1.09 to 2.81), suggesting a benefit from hCG. There was a significantly higher risk of ovarian hyperstimulation syndrome (OHSS) when hCG was used (Peto OR 3.62, 95% CI 1.85 to 7.06).There were eight studies (875 women) in the second comparison, progesterone versus placebo or no treatment. The results suggested a significant effect in favour of progesterone for the live birth rate (Peto OR 2.95, 95% CI 1.02 to 8.56) based on one study. For clinical pregnancy (CPR) the results also suggested a significant result in favour of progesterone (Peto OR 1.83, 95% CI 1.29 to 2.61) based on seven studies. For the other outcomes the results indicated no difference in effect.The third comparison (15 studies, 2117 women) investigated progesterone versus hCG regimens. The hCG regimens were subgrouped into comparisons of progesterone versus hCG and progesterone versus progesterone + hCG. The results did not indicate a difference of effect between the interventions, except for OHSS. Subgroup analysis of progesterone versus progesterone + hCG showed a significant benefit from progesterone (Peto OR 0.45, 95% CI 0.26 to 0.79).The fourth comparison (nine studies, 1571 women) compared progesterone versus progesterone + oestrogen. Outcomes were subgrouped by route of administration. The results for clinical pregnancy rate in the subgroup progesterone versus progesterone + transdermal oestrogen suggested a significant benefit from progesterone + oestrogen. There was no evidence of a difference in effect for other outcomes.Six studies (1646 women) investigated progesterone versus progesterone + GnRH agonist. We subgrouped the studies for single-dose GnRH agonist and multiple-dose GnRH agonist. For the live birth, clinical pregnancy and ongoing pregnancy rate the results suggested a significant effect in favour of progesterone + GnRH agonist. The Peto OR for the live birth rate was 2.44 (95% CI 1.62 to 3.67), for the clinical pregnancy rate was 1.36 (95% CI 1.11 to 1.66) and for the ongoing pregnancy rate was 1.31 (95% CI 1.03 to 1.67). The results for miscarriage and multiple pregnancy did not indicate a difference of effect.The last comparison (32 studies, 9839 women) investigated different progesterone regimens:intramuscular (IM) versus oral administration, IM versus vaginal or rectal administration, vaginal or rectal versus oral administration, low-dose vaginal versus high-dose vaginal progesterone administration, short protocol versus long protocol and micronized progesterone versus synthetic progesterone. The main results of this comparison did not indicate a difference of effect except in some subgroup analyses. For the outcome clinical pregnancy, subgroup analysis of micronized progesterone versus synthetic progesterone showed a significant benefit from synthetic progesterone (Peto OR 0.79, 95% CI 0.65 to 0.96). For the outcome multiple pregnancy, the subgroup analysis of IM progesterone versus oral progesterone suggested a significant benefit from oral progesterone (Peto OR 4.39, 95% CI 1.28 to 15.01).

AUTHORS' CONCLUSIONS

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 estrogen or hCG did not seem to improve outcomes. We also found no evidence favouring a specific route or duration of administration of progesterone. We found that 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.

Review of the evidence base of strategies to prevent ovarian hyperstimulation syndrome

The English-language literature was reviewed to examine the evidence base for strategies that have been used to prevent ovarian hyperstimulation syndrome (OHSS). Prediction of OHSS by pretreatment patient characteristics and ovarian response parameters is unreliable, with a significant number of OHSS cases occurring in patients not thought to be high risk, while the majority of 'high-risk' cycles do not result in OHSS. Alternatives to ovarian stimulation should always be considered, depending on the clinical situation. Monofollicular ovulation induction with a cautious step-up regime carries a lower risk of overstimulation than step-down regimes. In in vitro fertilization (IVF) cycles, a low starting dose of follicle-stimulating hormone (FSH) and the use of 5000 iu human chorionic gonadotrophin (hCG) for final follicular maturation may benefit patients at high risk of OHSS. The role of GnRH antagonists is unclear. In women with polycystic ovaries, who are undergoing ovarian stimulation for IVF, metformin co-treatment may reduce the risk of OHSS. Coasting of cycles with over-response is associated with a reduced risk of OHSS, although precise criteria for initiating and ending coasting are not definable at present. Elective cryopreservation of all embryos prevents late OHSS, but its value has been poorly researched. The literature does not support a role for intravenous albumin, administered around the time of oocyte retrieval, in preventing OHSS. Evidence is insufficient regarding a possible role for hexa-ethyl starch. hCG should not be used for luteal support, as it is associated with a higher risk of OHSS, and equivalent pregnancy rates are obtained with the use of progesterone.

WITHDRAWN: Luteal phase support in assisted reproduction cycles

BACKGROUND

The aspiration of the granulosa cells that surround the oocyte and the use of gonadotropin releasing hormone agonists (GnRHa) during assisted reproduction technology (ART) treatment can interfere with the production, during the luteal phase, of progesterone, which is necessary for successful implantation of the embryo. Providing hormonal supplementation during the luteal phase with either progesterone itself, or human chorionic gonadotropin (hCG), which stimulates progesterone production, may improve implantation and, thus, pregnancy rates.

OBJECTIVES

To determine (1) if luteal phase support after assisted reproduction increases the pregnancy rate, (2) the optimal hormone for luteal phase support, i.e. hCG, progesterone, or a combination of both, and (3) the optimal route of progesterone administration.

SEARCH STRATEGY

We searched the Cochrane Menstrual Disorders & Subfertility Group trials register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (1971 to Dec 2003), EMBASE (1985 to Dec 2003). We handsearched reference lists of relevant articles were scanned, and abstract books from scientific meetings up to December 2003.

SELECTION CRITERIA

Randomized controlled trials of luteal phase support after ART treatment, comparing hCG or progesterone with placebo or no treatment, comparing progesterone with hCG, progesterone plus hCG, or progesterone plus estrogen, or comparing different routes of progesterone administration. Quasi-randomized trials were excluded from the main analyses, but included in a secondary analysis for each comparison.

DATA COLLECTION AND ANALYSIS

For each comparison, data on live birth, ongoing and clinical pregnancy per embryo or gamete transfer procedure, miscarriage per clinical pregnancy, ovarian hyperstimulation syndrome (OHSS) per transfer, and multiple pregnancy per clinical pregnancy were extracted into 2 x 2 tables and subgrouped by use of GnRHa in the ovarian stimulation regimen. The odds ratio (OR) and risk difference (RD) were calculated.

MAIN RESULTS

Fifty-nine studies were included in the review. Luteal phase support with hCG provided significant benefit, compared to placebo or no treatment, in terms of increased ongoing pregnancy rates (odds ratio (OR) 2.38, 95% confidence interval (CI) 1.32 to 4.29) and decreased miscarriage rates (OR 0.12, 95% CI 0.03 to 0.50), but only when GnRHa was used. The odds of OHSS increased 20-fold when hCG was used in cycles with GnRHa. Progesterone use resulted in a small but significant increase in pregnancy rates (OR 1.34, 95% CI 1.01 to 1.79) when trials with and without GnRHa were grouped together, but no effect on the miscarriage rate was observed. No significant difference was found between progesterone and hCG or between progesterone and progesterone plus hCG or estrogen in terms of pregnancy or miscarriage rates, but the odds of OHSS were more than 2-fold higher with treatments involving hCG than with progesterone alone(OR 3.06, 95% CI 1.59 to 5.86). Comparing routes of progesterone administration, reductions in clinical pregnancy rate with the oral route, compared to the intramuscular or vaginal routes, did not reach statistical significance, but there was evidence of benefit of the intramuscular over the vaginal route for the outcomes of ongoing pregnancy and live birth. No significant difference in pregnancy rate was observed between vaginal progesterone gel and other types of vaginal progesterone.

AUTHORS' CONCLUSIONS

Luteal phase support with hCG or progesterone after assisted reproduction results in an increased pregnancy rate. hCG does not provide better results than progesterone, and is associated with a greater risk of OHSS when used with GnRHa. The optimal route of progesterone administration has not yet been established.

Estrogen-induced abnormally high cystic fibrosis transmembrane conductance regulator expression results in ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome (OHSS) remains one of the most life-threatening and potentially fatal complications of assisted reproduction treatments, arising from excessive stimulation of the ovaries by exogenous gonadotropins administrated during in vitro fertilization procedures, which is characterized by massive fluid shift and accumulation in the peritoneal cavity and other organs, including the lungs and the reproductive tract. The pathogenesis of OHSS remains obscure, and no definitive treatments are currently available. Using RT-PCR, Western blot, and electrophysiological techniques we show that cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated chloride channel expressed in many epithelia, is involved in the pathogenesis of OHSS. Upon ovarian hyperstimulation, rats develop OHSS symptoms, with up-regulated CFTR expression and enhanced CFTR channel activity, which can also be mimicked by administration of estrogen, but not progesterone, alone in ovariectomized rats. Administration of progesterone that suppresses CFTR expression or antiserum against CFTR to OHSS animals results in alleviation of the symptoms. Furthermore, ovarian hyperstimulation does not induce detectable OHSS symptoms in CFTR mutant mice. These findings confirm a critical role of CFTR in the pathogenesis of OHSS and may provide grounds for better assisted reproduction treatment strategy to reduce the risk of OHSS and improve in vitro fertilization outcome.

Luteal phase support in assisted reproduction cycles

BACKGROUND

The aspiration of the granulosa cells that surround the oocyte and the use of gonadotropin releasing hormone agonists (GnRHa) during assisted reproduction technology (ART) treatment can interfere with the production, during the luteal phase, of progesterone, which is necessary for successful implantation of the embryo. Providing hormonal supplementation during the luteal phase with either progesterone itself, or human chorionic gonadotropin (hCG), which stimulates progesterone production, may improve implantation and, thus, pregnancy rates.

OBJECTIVES

To determine (1) if luteal phase support after assisted reproduction increases the pregnancy rate, (2) the optimal hormone for luteal phase support, i.e. hCG, progesterone, or a combination of both, and (3) the optimal route of progesterone administration.

SEARCH STRATEGY

We searched the Cochrane Menstrual Disorders & Subfertility Group trials register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (1971 to Dec 2003), EMBASE (1985 to Dec 2003). We handsearched reference lists of relevant articles were scanned, and abstract books from scientific meetings up to December 2003.

SELECTION CRITERIA

Randomized controlled trials of luteal phase support after ART treatment, comparing hCG or progesterone with placebo or no treatment, comparing progesterone with hCG, progesterone plus hCG, or progesterone plus estrogen, or comparing different routes of progesterone administration. Quasi-randomized trials were excluded from the main analyses, but included in a secondary analysis for each comparison.

DATA COLLECTION AND ANALYSIS

For each comparison, data on live birth, ongoing and clinical pregnancy per embryo or gamete transfer procedure, miscarriage per clinical pregnancy, ovarian hyperstimulation syndrome (OHSS) per transfer, and multiple pregnancy per clinical pregnancy were extracted into 2 x 2 tables and subgrouped by use of GnRHa in the ovarian stimulation regimen. The odds ratio (OR) and risk difference (RD) were calculated.

MAIN RESULTS

Fifty-nine studies were included in the review. Luteal phase support with hCG provided significant benefit, compared to placebo or no treatment, in terms of increased ongoing pregnancy rates (odds ratio (OR) 2.38, 95% confidence interval (CI) 1.32 to 4.29) and decreased miscarriage rates (OR 0.12, 95% CI 0.03 to 0.50), but only when GnRHa was used. The odds of OHSS increased 20-fold when hCG was used in cycles with GnRHa. Progesterone use resulted in a small but significant increase in pregnancy rates (OR 1.34, 95% CI 1.01 to 1.79) when trials with and without GnRHa were grouped together, but no effect on the miscarriage rate was observed. No significant difference was found between progesterone and hCG or between progesterone and progesterone plus hCG or estrogen in terms of pregnancy or miscarriage rates, but the odds of OHSS were more than 2-fold higher with treatments involving hCG than with progesterone alone(OR 3.06, 95% CI 1.59 to 5.86). Comparing routes of progesterone administration, reductions in clinical pregnancy rate with the oral route, compared to the intramuscular or vaginal routes, did not reach statistical significance, but there was evidence of benefit of the intramuscular over the vaginal route for the outcomes of ongoing pregnancy and live birth. No significant difference in pregnancy rate was observed between vaginal progesterone gel and other types of vaginal progesterone.

REVIEWERS' CONCLUSIONS

Luteal phase support with hCG or progesterone after assisted reproduction results in an increased pregnancy rate. hCG does not provide better results than progesterone, and is associated with a greater risk of OHSS when used with GnRHa. The optimal route of progesterone administration has not yet been established.