Oocyte maturity, oocyte fertilization and cleavage-stage embryo morphology are better in natural compared with high-dose gonadotrophin stimulated IVF cycles

RESEARCH QUESTION

Does high-dose gonadotrophin stimulation have an effect on oocyte and early-stage embryo development?

DESIGN

This was a retrospective study including 616 natural cycle IVF (NC-IVF) and 167 conventional IVF (cIVF) cycles. In total, 2110 oocytes were retrieved and analysed in fresh cycles. In NC-IVF, only human chorionic gonadotrophin was applied to trigger ovulation. In cIVF, antagonist protocols with daily 150-300 IU of human menopausal gonadotrophins were performed. The effect of gonadotrophins on oocyte and early-stage embryo development was analysed. Primary outcomes were the occurrence of mature (metaphase II) oocytes, zygotes and embryos with good morphology at the cleavage stage 2 days after oocyte retrieval.

RESULTS

The mature oocyte rate (number of mature oocytes/number of retrieved oocytes) was higher in NC-IVF than cIVF cycles (89% versus 82%, adjusted odds ratio [aOR] 1.79, P = 0.001), as was the zygote rate per oocyte retrieved (70% versus 58%, aOR 1.76, P = 0.001) and the zygote rate per mature oocyte (79% versus 71%, aOR 1.62, P = 0.001). The percentage of zygotes that developed into cleavage-stage embryos was no different. For the transferred embryos, the probability of having a good embryo morphology with four blastomeres and a fragmentation of <10% (score 0) in cleavage-stage embryos was found to be higher in NC-IVF (proportional aOR for four blastomeres 2.00, P < 0.001; aOR 1.87 for a fragmentation score of 0, P = 0.003).

CONCLUSIONS

Oocyte maturity, oocyte fertilization and morphology of the cleavage-stage embryo are affected by high-dose gonadotrophin stimulation in fresh IVF cycles.

Gonadotropin Stimulation Reduces the Implantation and Live Birth Rate but Not the Miscarriage Rate of Embryos Transferred When Compared to Unstimulated In Vitro Fertilization

Research suggests that gonadotropin stimulation in in vitro fertilization (IVF) treatment affects embryo quality and the endometrium that might influence embryo implantation, placentation and establishment of a viable pregnancy. We assessed the impact of gonadotropin stimulation on implantation, live birth and miscarriage rates per transferred embryo by comparing stimulated and unstimulated IVF treatment. In a cohort of 728 couples, 1310 IVF cycles with successful embryo transfer were analysed; 857 cycles were stimulated with gonadotropins > 75 IU/day (333 poor responder < 4 oocytes; 524 normal responders), and 453 were unstimulated. In total, 1913 fresh cleavage-stage embryos were transferred. Zygote but no embryo selection was performed, and supernumerous zygotes were vitrified. The implantation rate was defined as number of sonographically detected amniotic sacs; live birth rate as number of children born per transferred embryo. Modified mixed effect Poisson regression was used to account for the dependency of cycles and embryos within the same women and the same transfer cycle. Adjustments were made for maternal age, parity, primary or secondary infertility and indication for IVF. Per transferred embryo, implantation rates (rate ratio (RR) 1.37; 95% CI 1.04-1.81; p = 0.028; aRR 1.42; 95% CI 1.10-1.84; p = 0.008) and live birth rates (RR 1.33; 95% CI 0.95-1.86; p = 0.093; aRR 1.38; 95% CI 1.01-1.88; p = 0.044) were higher in NC-IVF compared to cIVF normal responders. Miscarriage did not differ (RR 0.99; 95% CI 0.59-1.65; p = 0.965; aRR 0.90; 95% CI 0.52-1.53 p = 0.698). Similar results were obtained in poor responders. The study suggests an impact of gonadotropin stimulation on the implantation potential of embryos.

Gonadotrophin stimulation reduces follicular fluid hormone concentrations and disrupts their quantitative association with cumulus cell mRNA

RESEARCH QUESTION

Do follicular fluid hormone concentrations and the mRNA expression of LHCG, FSH and androgen receptors, aromatase and anti-Müllerian hormone (AMH) in cumulus granulosa cells differ in naturally matured and stimulated follicles?

DESIGN

Cross-sectional study involving 57 natural cycle IVF (NC-IVF) and 36 conventional gonadotrophin-stimulated IVF (cIVF) cycles performed between 2014 and 2016. cIVF was performed by ovarian stimulation with human menopausal gonadotrophin and gonadotrophin-releasing hormone antagonists. Hormone concentrations were determined in the follicular fluid of the leading follicle, and mRNA concentrations were quantified by reverse transcription polymerase chain reaction in RNA extracted from granulosa cells of the cumulus oophorus complex obtained from these fluids.

RESULTS

Follicular fluid hormone concentrations were significantly lower in cIVF compared with NC-IVF follicles. Median concentrations were 0.50 and 14.5 mIU/ml for LH (P < 0.001), 16.1 and 46.5 nmol/l for testosterone (P < 0.001), 1270 and 2675 nmol/l for oestradiol (P < 0.001), and 12.3 and 28.9 pmol/l for AMH (P < 0.001), respectively. In cumulus granulosa cells, mRNA concentrations for LH receptor, FSH receptor, androgen receptor, aromatase and AMH did not differ between cIVF and NC-IVF follicles. Several hormone and mRNA concentrations were quantitatively associated in natural cycles such as follicular fluid AMH and cumulus granulosa cells AMH RNA (r² = 0.107, P = 0.013), follicular fluid testosterone and cumulus granulosa cell AMH RNA (r² = 0.158, P = 0.002), follicular fluid oestradiol and cumulus granulosa cell AMH RNA (r² = 0.105, P = 0.014) and follicular fluid oestradiol and aromatase (r² = 0.113, P = 0.011). In contrast, these associations were not observed in stimulated cycles.

CONCLUSION

These findings indicate some effects of gonadotrophin stimulation on follicular physiology, which could be a cause for the previously suggested lower oocyte quality in cIVF compared with NC-IVF.

Retrospective outcome in women aged 45 years and older undergoing natural cycle IVF treatment

RESEARCH QUESTION

Is natural cycle IVF treatment beneficial to middle-aged women with poor ovarian response?

DESIGN

Retrospective investigation of outcomes in women aged 45 years and older, who underwent natural cycle IVF treatment between 2009 and 2018 in a single assisted reproduction clinic with the aim of reporting several successful outcomes.

RESULTS

In total, 2408 IVF retrievals in women aged 45 years and older were included in this study. Mean serum FSH level on day 3 was 21.4 ± 12.5 (range: 0.3-93.7) IU/ml. One fresh cleavage-stage embryo was transferred in 37.4% (900/2408) of the initiated cycles. The overall clinical pregnancy rate and live birth rate per fresh embryo transfer were 2.8% (25/900) and 0.8% (7/900), respectively. Natural cycle IVF treatment led to seven successful deliveries during the period. All seven women who successfully delivered were poor ovarian responders who met the diagnostic Bologna criteria and, among them, three had elevated serum FSH levels on day 3 (range: 39.0-47.1 mIU/ml). All seven had full-term delivery, and no congenital abnormalities were observed in their infants. No significant difference was found in serum FSH level on day 3 between those with and without positive beta-HCG test results.

CONCLUSIONS

These findings suggest that natural cycle IVF treatment could be an option for older poor responders in countries that do not permit egg donation. Careful counselling is required, however, because of the low probability of live births after IVF in middle-aged women.

The endocrine milieu in naturally matured follicles is different in women with high serum anti-Müllerian hormone concentrations

RESEARCH QUESTION

Is the endocrine milieu different in women with low serum anti-Müllerian hormone (AMH) concentration compared with women with high concentration?

DESIGN

Cohort study of 84 women (four groups) classified according to AMH concentration and age undergoing natural cycle IVF treatment. Concentrations of LH, oestradiol, testosterone, androstenedione and AMH were determined in follicular fluid (FF), associations analysed and clinical outcome parameters evaluated.

RESULTS

A positive correlation between serum and FF AMH concentrations was confirmed. Follicular fluid androstenedione concentration was positively correlated with serum AMH concentration (P < 0.0001, r² = 0.197). The correlation between FF LH and FF testosterone concentration in all women was not significant (P = 0.050, r² = 0.046); however, the correlation between FF androstenedione in women with high serum AMH concentration was significant (P = 0.032, r² = 0.220). Follicular fluid testosterone and androstenedione were positively correlated with FF oestradiol overall and in some individual groups. The high serum AMH concentration group showed the highest FF AMH and androstenedione concentrations and lowest oestradiol-testosterone and oestradiol-androstenedione ratios. High FF AMH concentration was associated with a higher clinical pregnancy rate and high FF oestradiol concentration with a slightly better embryo quality.

CONCLUSIONS

Differences in the endocrine milieu in women with high serum AMH concentration seem to be caused by increased follicular LH concentration. In women with high serum AMH concentration, FF androstenedione is increased and ratios of oestradiol-testosterone and oestradiol-androstenedione are decreased, suggesting a disturbed endocrine milieu caused by reduced metabolization of FF androgens into oestrogens. In natural cycles, FF AMH concentrations are positively associated with higher clinical pregnancy rates and oestradiol concentrations with a higher embryo score.

Impact of embryo quality and endometrial thickness on implantation in natural cycle IVF

Purpose

The aim of this study is to assess the effect of the endometrial thickness and embryo quality on the implantation potential in natural cycle IVF (NC-IVF).

Methods

A retrospective single-center study was performed on 552 single embryo transfers after NC-IVF. The ‘quality' of the embryos was evaluated trough the number and regularity of blastomeres, degree of fragmentation, and nuclear content of cells. Endometrial thickness was measured in millimeters with transvaginal ultrasound on the day of hCG application.

Results

Our findings showed a statistically significant difference in successful implantation until a plateau of 10 mm is reached (p = 0.001). Only one pregnancy was achieved where endometrial thickness was less than 7 mm, and this resulted in an early miscarriage. The predictors of favorable implantation were fragmentation (≤ 10%, p < 0.05) and the number of blastomeres (preferably 8-cell, p < 0.01) on day 3. Embryo quality (R = 0.052) and endometrial thickness (R = 0.18) were closely related to pregnancy rate. The overall implantation rate per embryo transfer was 18.8%.

Conclusions

Embryo quality and endometrial thickness have a significant impact on implantation in NC-IVF. Highest implantation potential has an 8-cell embryo with ≤ 10% fragmentation in the third day following oocyte retrieval. Endometrial thickness of at least 7 mm seems to be the optimal edge of successful pregnancy.

Serum and follicular fluid testosterone concentrations do not correlate, questioning the impact of androgen supplementation on the follicular endocrine milieu

Basic research into a possible link between serum and follicular fluid androgen concentrations to detemine whether androgen supplementation in low responders affects follicular endocrine milieu is still lacking. Ninety-seven women (aged 28-43 years) undergoing one natural IVF cycle without any hormone stimulation were analysed. Serum and follicular fluid were collected at the time of follicle aspiration, and the concentrations of LH, total testosterone, oestradiol, dehydroepiandrosterone and anti-Mullerian hormone (AMH) were determined. Serum LH (P = 0.003) and AMH (P = 0.026) concentrations, and follicular fluid AMH (P = 0.015) decreased with increasing age. Within follicular fluid, total testosterone was correlated with oestradiol (P < 0.001) and AMH (P = 0.010); LH correlated with AMH (P = 0.005). Correlation analysis of serum and follicular fluid hormone concentrations revealed that LH, oestradiol and AMH correlated (P < 0.001), whereas testosterone did not. Testosterone serum concentrations did not correlate with other follicular fluid hormones, such as dehydroepiandrosterone, oestradiol and AMH, whereas serum LH correlated with follicular flulid AMH (P < 0.008). Follicular fluid hormone concentrations seem to be independent from serum testosterone. Therefore, it is questionable whether an increase in serum testosterone concentration by androgen supplementation could improve the follicular endocrine milieu.

Follicular flushing in natural cycle IVF does not affect the luteal phase - a prospective controlled study

In contrast to multifollicular IVF, follicular flushing seems to increase the efficacy of monofollicular IVF treatments such as natural cycle IVF (NC-IVF). However, because follicular flushing causes loss of granulosa cells, it might negatively affect luteal phase length and endocrine function of the luteal body. A prospective cohort Phase II study was performed in 24 women undergoing NC-IVF. Women underwent a reference cycle with human chorionic gonadotrophin-induced ovulation without follicle aspiration and analysis of the length of the luteal phase and luteal concentrations of progesterone and oestradiol. In addition, they underwent a NC-IVF cycle which was performed identically but follicles were aspirated and flushed three times. The luteal phase was shorter in 29.2%, equal in 16.7% and longer in 50.0% of cases following flushing of the follicles. Overall, neither difference in luteal phase length was significant [median duration (interquartile range) in reference cycle: 13 (12; 14.5), IVF (flushing) cycle: 14 (12.5; 14.5), median difference (95% CI): 0.5 (-0.5 to 1.5)] nor median progesterone and oestradiol concentrations. In conclusion, follicular flushing in NC-IVF affects neither the length of the luteal phase nor the luteal phase concentrations of progesterone and oestradiol, questioning the need for luteal phase supplementation.

Intrafollicular inflammatory cytokines but not steroid hormone concentrations are increased in naturally matured follicles of women with proven endometriosis

PURPOSE

The aim of this study was to assess whether the intrafollicular cytokine profile in naturally developed follicles is different in women with endometriosis, possibly explaining the lower reproductive outcome in endometriosis patients.

METHODS

A matched case-control study was conducted at a university-based infertility and endometriosis centre. The study population included 17 patients with laparoscopically and histologically confirmed endometriosis (rAFS stages II-IV), each undergoing one natural cycle IVF (NC-IVF) treatment cycle between 2013 and 2015, and 17 age-matched NC-IVF women without diagnosed endometriosis (control group). Follicular fluid and serum was collected at the time of follicle aspiration. The concentrations of inflammatory cytokines (IL-1β, IL-6, IL-8, IL-15, IL-18, TNF-α) and hormones (testosterone, estradiol, AMH) were determined in follicular fluid and serum by single or multiplexed immunoassay and compared between both groups.

RESULTS

In the follicular fluid, IL-1β and IL-6 showed significantly (P < 0.001 and 0.01, respectively) higher median concentrations in the endometriosis group than in the control group and a tendency towards endometriosis severity (rAFS stage) dependence. The levels of the interleukins detectable in follicular fluid were significantly higher than those in the serum (P < 0.01). Follicular estradiol concentration was lower in severe endometriosis patients than in the control group (P = 0.036). Follicular fluid IL-1β and IL-6 levels were not correlated with estradiol in the same compartment in neither patient group.

CONCLUSIONS

In women with moderate and severe endometrioses, some intrafollicular inflammatory cytokines are upregulated and not correlated with intrafollicular hormone concentrations. This might be due to the inflammatory microenvironment in endometriosis women, affecting follicular function and thereby possibly contributing to the reproductive dysfunction in endometriosis.

Age, independent from ovarian reserve status, is the main prognostic factor in natural cycle in vitro fertilization

OBJECTIVE

To analyze natural cycle IVF (NC-IVF) results according to patient age, ovarian reserve status following the Bologna criteria, cause of infertility, and modification of the cycle with the use of GnRH antagonist.

DESIGN

Retrospective cohort study.

SETTING

Tertiary-care university hospital.

PATIENT(S)

Nine hundred forty-seven natural cycles carried out in 320 patients.

INTERVENTION(S)

Analysis of 947 NC-IVF outcomes performed in one single center between January 2010 and December 2014.

MAIN OUTCOME MEASURE(S)

Pregnancy rates per cycle started, per ET, and per patient, as well as ongoing pregnancy rate at a minimum of 12 weeks of gestation.

RESULT(S)

Among the three age groups analyzed (≤35 years, 36-39 years, and ≥40 years), pregnancy rates per cycle were significantly lower in the older group of patients (11.4% vs. 11.6% vs. 5.9%). In addition, miscarriage rate (7.7% vs. 34.4% vs. 50%) and ongoing pregnancy rate (10.6% vs. 7.6%vs. 3.0%) were negatively affected by patient age. However, no differences were observed according to patient ovarian reserve status, cause of infertility, or modification of the cycle with GnRH antagonist. The multivariate logistic regression confirmed that patient age was the only variable that could predict pregnancy in NC-IVF cycles (odds ratio, 0.93; 95% confidence interval, 0.88-0.98).

CONCLUSION(S)

NC-IVF is a feasible and "patient-friendly" option to be offered to young patients, independent of their ovarian reserve status.