Among high responders, is oocyte development potential different in Rotterdam consensus PCOS vs non-PCOS patients undergoing IVF?

Purpose To evaluate the oocyte potential to develop to blastocyst in Rotterdam consensus PCOS in women with hyper-responses requiring freeze-all embryos.

Retrospective, single-academic center, cohort study of 205 patients who underwent freeze-all antagonist IVF cycles for OHSS risk between 2013 and 2019. Women in the PCOS group (n = 88) were diagnosed per the 2003 Rotterdam criteria. Control patients (n = 122) had no evidence of hyperandrogenism or menstrual disturbance. Data was compared by t-tests, chi-squared tests, or multivariate logistic regression (SPSS). Frozen blastocysts were Gardner’s grade BB or better.

There was no difference in terms of number of oocytes collected (PCOS vs non-PCOS 27.7 ± 9.4 vs 25.9 ± 8.2, p = 0.157), number of MII (20.7 ± 8.0 vs 19.1 ± 6.6, p = 0.130), number of 2PN fertilized (15.6 ± 7.4 vs 14.4 ± 5.9, p = 0.220), and number of frozen blastocysts (7.8 ± 4.9 vs 7.1 ± 3.8, p = 0.272). In addition, fertilization rates (74 ± 17% vs 75 ± 17%, p = 0.730), blastulation rates per 2PN (51 ± 25% vs 51 ± 25%, p = 0.869), and blastulation rates per mature oocytes (37 ± 18% vs 37 ± 15%, p = 0.984) were all comparable between PCOS and controls, respectively. Moreover, there was no difference when comparing PCOS and controls in pregnancy rates (45/81 vs 77/122, p = 0.28) and clinical pregnancy rates (34/81 vs 54/122, p = 0.75), respectively. Multivariate logistic regression controlling for confounders failed to alter these results.

PCOS subjects do not seem to have altered oocyte potential as measured by number of MII oocytes collected, fertilization, and blastulation rates when compared to high-responder controls, with similar magnitude of stimulation.

PCOS, PCOM, OHSS, IVF, Fertilization rate, Oocyte quality

Polycystic ovary syndrome (PCOS) prevalence is reported to be between 4 and 18% of reproductive age women and is the most common cause for ovulatory-related infertility and the most common endocrinopathy in reproductive age women [1]. First-line treatment options for PCOS-related infertility include ovulation induction via oral medications, while second line relies on gonadotrophin-mediated ovulation induction [2]. IVF can be offered as a third-line option to PCOS patients who have failed ovulation induction, or who have other indications for IVF. Performing controlled ovarian stimulation (COS) for IVF in patients with PCOS can be challenging, mainly because of their propensity to develop ovarian hyperstimulation syndrome (OHSS). PCOS women have a dramatically different metabolic milieu, when compared with non-PCOS patients. Among other factors, they show higher serum androgen levels [3]. They are often insulin-resistant, and as such have higher circulating serum insulin levels, as well as other circulating inflammatory markers when compared to age- and BMI-matched controls [1, 4]. This higher circulating insulin levels that are seen in insulin resistance can affect the IGF-1 receptor which play crucial roles in folliculogenesis [5]. PCOS patients display increased LH pulsatility favoring increased androgen production [6, 7]. All these factors probably alter the follicular environment and could thus exert a deleterious effect on the oocyte development and competence. PCOS patients undergoing IVF generally produce high number of follicles; however, the oocytes obtained from them have been suspected of poorer quality, possibly leading to lower fertilization rates and poorer embryo development and even lower live birth rates [8, 9]. Nevertheless, whether PCOS patients demonstrate lower oocyte potential when compared non-PCOS patients remains highly controversial. Published studies have been confounded by varying magnitudes of stimulation between PCOS and controls, which can affect IVF outcomes and oocyte potential. Many of the published studies were using long GnRH agonist IVF protocols, which are rarely used nowadays in this patient population. This study was designed to specifically address the role of PCOS on oocyte yield and competence, among high-responders, in GnRH antagonist/freeze-all cycles.

This retrospective cohort study includes 83 PCOS patients and 122 control patients who underwent an IVF treatment between 2013 and 2019 in a single-academic center (McGill University—affiliated reproductive center). All patients underwent a freeze-all cycle because of OHSS high risk. Inclusion criteria were 15 or more eggs retrieved, use of a GnRH antagonist protocol, freeze-all cycles. PCOS subjects were diagnosed based on the 2003 Rotterdam criteria. Control “PCOM” group subjects did not report menstrual irregularity and did not have clinical or biochemical evidence of hyperandrogenism. Exclusion criteria were women stimulated with other IVF protocols than listed in the inclusion criteria, including the long GnRH agonist protocol and the microdose flare protocols, as well as subjects that had a fresh embryo transfer, patients with severe male factor infertility, or had less than 5 million total motile sperm counts. Patients with frozen embryos less than Gardner’s grade 3BB were excluded. Baseline ultrasound was performed for all the women included in the study in the early follicular phase. This was done to evaluate the uterus and the antral follicle count (AFC) and any other relevant pelvic pathology such as fibroids, endometriosis, endometrial polyps, or ovarian cysts. AFC was calculated manually by experienced pelvis ultrasonographers. In vitro fertilization procedures A fixed antagonist protocol for ovarian hyperstimulation was used. Gonadotropins were initiated on days 2–3 of a spontaneous or progestin-induced menstrual cycle and the GnRH antagonist was initiated on the sixth day of the gonadotrophin administration (Orgalutran, Organon, Canada or Cetrotide, Merk Serono, Canada). Patients were stimulated with recombinant FSH (Gonal-F, Merk Serono, Canada & Puregon, Organon, Canada). Ovulation trigger was done with Buserelin (Suprefact, Sanofi-Aventis, Canada) in the majority of our cohort, while urinary 5000 IU hCG (Ferring, Canada) and recombinant hCG 250 mcg SQ (Ovidrel, Serono, Canada) were used in 10 and 19 (4.8 and 9.1%) of patients respectively and did not differ between groups (p > 0.05). Transvaginal ultrasound–guided oocyte retrieval was performed 36 h post-trigger. Fertilization was done by conventional IVF or ICSI according to standard indications. Fertilization was assessed 16–18 h after collection. A single-step medium (Cooper Surgical) was used to culture all embryos until blastocyst stage in bench top incubators. Pregnancy was defined as a serum beta-human chorionic gonadotropin level of at least 20 IU/L on day 16 embryo age and clinical pregnancy was defined as an intra-uterine gestational sac with a fetal pole with a heartbeat detected with a transvaginal ultrasound at 6 to 7 weeks gestational age. Outcome measures and statistical analysis Demographic and clinical parameters were recorded. Calculations were performed using SPSS 23.0 (IBM Corporation, USA). Statistical analysis was performed with independent t-tests to compare continuous baseline variables and chi-squared tests to compare categorical variables. For continuous variables, the p value was based on Levene’s test for equality of variances. Continuous data was confirmed for normal distribution using the Kolmogorov–Smirnov test. Stepwise multivariate logistic regression was used to calculate outcomes while controlling for the following factors: basal serum FSH and LH levels, AFC, and the diagnosis of endometriosis. Total FSH dose to stimulate and AFC were correlated and as such only AFC was selected. Data are presented as mean ± standard deviation. Two-sided p values < 0.05 were accepted as significant. After determining that we had 88 patients with PCOS and a total population of 205 subjects, we calculated using a power 0.80 and alpha 0.05 for a two-sided test of means that we had a Cohen’s d of 0.39. Ethics approval was obtained from our institution (REB 2020–5971) for this study and the data collection.

During the study period, 88 women with PCOS and 122 normal ovulatory controls underwent an IVF antagonist protocol with freeze-all for OHSS risk and met the inclusion criteria. When comparing baseline characteristics of the PCOS patients to those with normal ovulation, PCOS subjects showed higher AFC counts (45 ± 19 vs 27 ± 12, p = 0.001) and required lower total doses of gonadotropins to stimulate (1332 ± 530 vs 1566 ± 612 IU, p = 0.01). They also showed slightly higher baseline serum FSH and LH levels (5.8 ± 1.6 vs 6.9 ± 2.0 IU/L, p = 0.001 and 8.6 ± 6.1 vs 5.9 ± 3.1 IU/L, p = 0.001). The age of the patient (p = 0.89), the number of previous pregnancies (p = 0.91), and the number of delivered babies (p = 0.91) were similar. In addition, baseline serum measures were similar between groups (E2, prolactin, testosterone, and TSH) (Table 1). Male age did not differ, nor did semen parameters (Table 1). Table 1. | PCOS (n = 88) | Controls (n = 122) | p | | |---|---|---|---| | Age (years) | 30.4 ± 3.2 | 30.3 ± 3.97 | 0.89 | | Parity | 0.20 ± 0.51 | 0.21 ± 0.52 | 0.91 | | Gravidit | 0.61 ± 0.99 | 0.63 ± 0.99 | 0.91 | | FSH (IU/L) | 5.8 ± 1.6 | 6.9 ± 2.0 | 0.001 | | LH (IU/L) | 8.6 ± 6.1 | 5.9 ± 3.1 | 0.001 | | E2 (rmol/L) | 231 ± 266 | 180 ± 133 | 0.11 | | Prolactin (µg/L) | 10.7 ± 4.9 | 11.2 ± 9.4 | 0.66 | | TSH (mIU/L) | 2.6 ± 5.7 | 1.8 ± 1.0 | 0.21 | | Testosterone total (nmol/L) | 1.65 ± 0.97 | 1.46 ± 0.64 | 0.16 | | AFC | 45 ± 19 | 27 ± 12 | 0.001 | | Male age (years) | 34.8 ± 5.9 | 35.0 ± 5.9 | 0.77 | | Sperm concentration (M/mL) | 41.1 ± 36.3 | 34.8 ± 35.6 | 0.23 | | Sperm motility (%) | 42.1 ± 27.2 | 34.5 ± 25.4 | 0.051 | | ICSI rate | 85 ± 51 | 79 ± 50 | 0.49 | | FSH total (IU) | 1332 ± 530 | 1566 ± 612 | 0.01 | | Peak E2 (rmol/L) | 12,517 ± 6076 | 11,251 ± 4174 | 0.10 | In terms of results when comparing the two groups, there was a higher number of follicles seen by ultrasound at trigger day when comparing PCOS with controls (p = 0.04). Despite this, a similar number of oocytes were collected (p = 0.16), a similar number of mature eggs (MII oocytes) were obtained (p = 0.13), a similar number of fertilized oocytes (2PN) occurred (p = 0.22), and a similar number of blastocysts were frozen (p = 0.27), when comparing PCOS patients with controls (Fig. 1). Moreover, fertilization and blastulation rates were similar between the two groups of patients (Table 2). Multivariate logistic regression controlling for confounders failed to alter these results. Table 2. | PCOS (n = 88) | Controls (n = 122) | p (chi-squared) | p (logistic regression) | aOR (95%CI) | | |---|---|---|---|---|---| | Fertilization rate (%) | 74.44 ± 17.00 | 75.2 ± 16.7 | 0.73 | 0.35 | 0.24 (0.02–3.6) | | Blastulation rate (%), per fertilized oocyte | 50.80 ± 24.66 | 51.4 ± 25.3 | 0.87 | 0.051 | 10.9 (0.99–120) | | Blastulation rate (%), per MII | 37.04 ± 17.96 | 37.09 ± 14.69 | 0.98 | 0.21 | 6.3 (0.35–116) | Among women who underwent an embryo transfer, there was no difference in the pregnancy rate when comparing PCOS and controls, respectively (45/81 vs 77/122, p = 0.28) or the clinical pregnancy rate (34/81 vs 54/122, p = 0.75) (Table 3). Table 3. | PCOS (n = 81) | Controls (n = 122) | p (chi-squared) | | |---|---|---|---| | Pregnancy rate (%) | 55.6 | 63.1 | 0.28 | | Clinical pregnancy rate (%) | 42 | 44.3 | 0.75 |

PCOS is characterized by an increased cohort of recruitable follicles and altered serum and ovarian hormonal environment. In parallel, the number and quality of mature oocytes has been proposed by some authors as being altered, leading to lower pregnancy rates and higher abortion rates [10, 11]. The concept of oocyte quality can be extrapolated from the oocyte developmental competence, or its capacity to undergo meiotic maturation, fertilization, and to pursue development until the blastocyst stage [12]. Conflicting data exists regarding a possible reduced oocyte quality in PCOS patients, and no consensus has been made. First regarding oocyte maturation rates, several studies have identified a reduced rate of mature oocytes in PCOS patients when compared with normal ovulatory patients [13, 14], while other groups have reported similar rates of mature oocytes [15]. However, these studies are compromised by varying magnitudes of stimulation between the PCOS and control subjects. Moreover, many retrospective studies have shown reduced fertilization rates for PCOS patients [8, 13, 15, 16]. A meta-analysis conducted in 2006 concluded similarly with altered oocyte potential as demonstrated by these measures in PCOS [9]. Conversely, other authors have reported no differences regarding fertilization rates in PCOS patients [17–20]. One study even found better fertilization rates in PCOS subjects when compared to controls [21], although this study included only ICSI cycles. All studies cited here included agonist-based protocols and compared PCOS patients with different control groups, mostly tubal infertility and/or male infertility patients. Our study selected a control group with a similar high ovarian response to gonadotrophin stimulation as the PCOS, to limit bias. Such a model can better discriminate the effect of the PCOS diagnosis per se instead of the high response to stimulation which in and of itself could impair oocyte potential. Our control group thus includes high-responders with normal ovulatory function, representing most probably a group of PCOM patients, i.e., patients with high count of follicles at baseline, without any known ovulation disorder or hyperandronenism. Of note, it has been already described that high-response to IVF stimulation does not appear to effect fertilization rates [22] or implantation rates [22]. To our knowledge, a single study published in 2010 has used similar control group and antagonist protocols; similar results to ours were reported; i.e., the authors did not find any differences in terms of number of eggs collected, fertilization rates, and the number of good-quality blastocysts obtained [23] when comparing the PCOS and control subjects. Our results are concordant with those. Our study is limited by its retrospective nature which may mask hidden bias, and a lack of information regarding complications like mild and moderate OHSS. Because AMH was not used regularly by our clinic at that time, we cannot provide data regarding AMH in our cohort. In addition, few subjects had weight or BMI data listed in their chart; thus, we cannot provide comparison for this parameter as well. Moreover, progesterone levels can play a role in the oocyte competence, but we cannot comment on this specific aspect as we do not routinely measure it during stimulation cycles in our clinic. Although the inclusion of subjects triggered with hCG and GnRH agonist could also be viewed as a limitation, rates of use of hCG triggering were comparable in both groups and we elected not to remove these subjects because it would have decreased the power of the study. One may ask about livebirth rates; however, due to a lack of staff in our clinic, they are not available for many subjects, with an unusual lag having occurred. The Cohen’s d calculated by the power analysis suggested that we have the ability to detect an effect size of 40%, which is below that seen in our study. However, it should be noted as related to our primary outcomes, number of oocytes collected, fertilized, good-quality blastocysts vitrified, and rates of fertilization and blastulation the two groups were almost the same. As such, even if we had a large enough group to detect a significant difference, this difference would not have been clinically significant. It is interesting to note that there was a difference in the percentage of mature follicles which lead to an oocyte being collected when comparing the PCOS and controls, favoring the control group. This can be determined because the PCOS had more stimulated follicles but an equal number of collected oocytes. This may be a marker of oocyte potential which we did not consider, although follicular count is a less reliable marker. Lastly, it would have been nice to have data of free androgen levels and DHEA- levels although there were not reliably collected particularly in the control subjects. Another interesting avenue could have been to use the PGT-A results as a marker of oocyte quality, but we do not have this data available for this cohort. Strengths of the study include an ideally matched control group, where they used modern protocols (GnRH antagonist) for subjects at risk for OHSS and all IVF cycles were treated similarly in both the PCOS and control groups. In conclusion, it seems that oocyte quality and potential obtained from PCOS subjects are similar to non-PCOS patients when treated with GnRH antagonist freeze-all IVF cycles. Declarations Conflict of interest The authors declare no competing interests. Footnotes Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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