Effects of letrozole cotreatment on endocrinology and follicle development in women undergoing ovarian stimulation in an antagonist protocol.

STUDY QUESTION: What are the downstream endocrine and paracrine consequences of letrozole (LZ) cotreatment during ovarian stimulation and is follicle growth and recruitment affected? SUMMARY ANSWER: Letrozole cotreatment induces marked changes in both the follicular and luteal phase endocrinology causing potentiation of follicle diameter and an improved corpus luteum function without affecting the secondarily recruited follicle cohort. WHAT IS KNOWN ALREADY: Letrozole is a third-generation aromatase inhibitor that is well-established as an effective ovulatory agent, while its possible benefits in standard in vitro fertilization protocols are less thoroughly investigated. STUDY DESIGN, SIZE, DURATION: This study included a double-blinded, placebo-controlled, randomized study with LZ or placebo intervention during ovarian stimulation for IVF treatment, an observational preceding baseline natural cycle and a succeeding follow-up visit. Participants were enrolled between August 2016 and November 2018. Data from the randomized, stimulated cycle were part of a larger RCT, which was previously published. PARTICIPANTS/MATERIALS, SETTING, METHODS: The study was conducted at a public fertility clinic at Herlev Hospital, Denmark, including 31 healthy, normo-responding women eligible for IVF treatment. They underwent a natural baseline cycle and were subsequently randomized to receive either LZ 5 mg (n = 16) or placebo (n = 15) daily during ovarian stimulation from cycle day (CD) 2-3 until induction of ovulation. Throughout both cycles, monitoring was performed every third day with transvaginal ultrasound for assessment of follicle count and diameter, and blood analyses for the determination of twelve endocrine and paracrine parameters. A follow-up assessment was performed at CD2-3 in the succeeding cycle. In the randomized part of the study, we determined differences in blood parameters, follicle recruitment, and follicle diameter. In the observational part of the study, we assessed follicle recruitment in between cycles and its correlation to endocrine parameters. MAIN RESULTS AND THE ROLE OF CHANCE: Letrozole cotreatment significantly suppressed oestradiol (E2) concentrations in the follicular phase (area under the curve (AUC) -58% (95% CI [-70%; -43%], P < 0.001)) and luteal phase (AUC -39% [-63%; -1%], P = 0.046). This had a marked effect on the endocrine and paracrine output with increased follicular phase luteinizing hormone (AUC +37% [3%; 82%], P = 0.033), androstenedione (AUC +36% [6%; 74%], P = 0.016), testosterone (AUC +37% [7%; 73%], P = 0.013) and 17-OH-progesterone (AUC +114% [10%; 318%], P = 0.027). Furthermore, follicle-stimulating hormone (FSH) was increased at stimulation day 5 in the LZ group (P < 0.05). In the luteal phase, increased corpus luteum output was reflected by elevated progesterone (AUC +44% [1%; 104%], P = 0.043), inhibin A (AUC +52% [11%; 108%], P = 0.011), androstenedione (AUC +31% [9%; 58%], P = 0.006) and testosterone (AUC +29% [6%; 57%], P = 0.012) in the LZ group. The altered balance between oestrogens and androgens was reflected in a markedly reduced SHBG concentration in the LZ group throughout the luteal phase (AUC -35% [-52%; -11%], P = 0.009). Endocrine and paracrine parameters were similar between groups at the follow-up visit. Letrozole cotreatment significantly increased the mean number of follicles >16 mm at oocyte retrieval (7.2 vs 5.2, difference: 2.0, 95% CI [0.1; 3.8], P = 0.036), while the mean total number of follicles at oocyte retrieval was the same (23.7 vs 23.5, difference: 0.2 [-5.8; 6.1], P = 0.958), and the mean FSH consumption during the stimulated cycle was similar (1500 vs 1520 IU, difference -20 IU [-175; 136], P = 0.794). Between cycles, the mean antral follicle count at CD2-3 was unchanged (natural cycle 19.0, stimulated cycle 20.9, follow-up cycle 19.7, P = 0.692) and there was no effect of LZ cotreatment on the recruitment of the next follicle cohort (test for interaction, P = 0.821). LIMITATIONS, REASONS FOR CAUTION: This study included a relatively small, selected group of healthy women with an expected normal ovarian function and reserve, and the effects of LZ may therefore be different in other patient groups. WIDER IMPLICATIONS OF THE FINDINGS: We confirm some previous findings concerning increased follicle growth and increased endogenous FSH and androgen production, which support the rationale for further studies on the use of LZ cotreatment, for example, as a form of endogenous androgen priming sensitizing the follicle to FSH. Letrozole appears to improve the luteal phase with better stimulation of corpus luteum and progesterone secretion. STUDY FUNDING/COMPETING INTEREST(S): The authors declare no conflicts of interest relating to the present work. TRIAL REGISTRATION NUMBER: NCT02939898.

Contribution of recruitable follicles to circulating anti-Müllerian hormone levels following maximal gonadotrophin stimulation in patients with limited ovarian reserve.

In women, the majority of anti-Müllerian hormone (AMH) measured in serum originate from small antral follicles measuring 2-10 mm. In gonadotrophin-stimulated cycles prior to assisted reproductive technology (ART), most of the recruitable follicles develop beyond 10 mm in size and thus lose their AMH secretion capacity causing declining serum AMH levels. The aim of this study was to define the residual serum AMH level after elimination of the AMH producing recruitable follicles following maximal gonadotrophin stimulation. We measured serum AMH and number of follicles according to size at several time points during a cycle of maximal gonadotrophin stimulation (fixed dose of 300 IE HP-hMG) in 107 women with low AMH (median AMH 5 pmol/L, interquartile range (IQR) 3.3-8.3). We found that AMH decreased gradually and reached a minimum level of -55.4% (95% CI -59.6; -50.7) of the baseline value four days after ovulation trigger. Our findings suggest that the residual AMH production origins from pre-antral and small antral follicles not visible by sonography and that they account for up to 40% of the circulating AMH.

The use of anti-Müllerian hormone for controlled ovarian stimulation in assisted reproductive technology, fertility assessment and -counseling.

Ovarian reserve can be determined by serum anti-Müllerian hormone (AMH) level and/or antral follicle count before controlled ovarian stimulation. The aim of controlled ovarian stimulation is to achieve an appropriate number of mature follicles and avoid complications such as ovarian hyperstimulation syndrome. Measurement of the ovarian reserve is useful for clinicians as it predicts the ovarian response to controlled ovarian stimulation. Further, it assists in giving the patient realistic expectations regarding the treatment. By determining the ovarian reserve, the most appropriate stimulation protocol and gonadotropin dose can be chosen specifically for each woman enabling so-called "individualized treatment" in line with the personalized treatment concept. Many benefits come with using AMH as a biomarker for ovarian reserve; the hormone is considered fairly cycle independent apart from a small decrease in the late follicular phase and there is no inter-observer variance. However, the use of AMH also has limitations; since the implementation of AMH in fertility treatment several AMH assays have been developed. This has made direct comparisons of AMH serum levels complicated. Currently, no international standardized assays exist. AMH is a valid predictor of the ovarian response to controlled ovarian stimulation and to some extent the chance of pregnancy in relation to assisted reproductive technology, but AMH is less optimal in prediction of spontaneous pregnancy and live birth after assisted reproductive technology. Accordingly, AMH can be used to optimize gonadotropin stimulation in fertility treatment, but is not recommended as a screening tool in the general population.

Circadian variation in concentration of anti-Müllerian hormone in regularly menstruating females: relation to age, gonadotrophin and sex steroid levels.

BACKGROUND: Anti-Müllerian hormone (AMH) is a promising marker of ovarian reserve. The aim of the study is to assess the circadian variation in AMH, and to evaluate its clinical relevance and biological aspects as an effect of age and other endocrine mechanisms involved in the regulation of AMH secretion. METHODS: Nineteen healthy non-smoking, regularly menstruating female volunteers with body mass index below 30 kg/m(2), 10 aged 20-30 years (Group A) and 9 aged 35-45 (Group B) were included. Blood sampling, initiated at 8:00 a.m. on Days 2-6 of the menstrual cycle, was continued every second hour until 8:00 a.m. the following day. Serum levels of AMH, FSH, LH, progesterone and estradiol were measured. RESULTS: With 8:00 a.m. values at the first day of investigation as a reference, the mean concentrations in the pooled data revealed a significantly lower level at 4:00 a.m. (P = 0.021) and 6:00 a.m. (P = 0.005) with a maximum mean difference of 1.9 pmol/l (10.6%). The same pattern was seen in both the age groups. Including both the age groups, the overall circadian variation of the AMH levels did not reach statistical significance (P = 0.059). A significant positive correlation between AMH and LH concentration was seen over the 24-h period (P < 0.001). CONCLUSIONS: A slight decrease in serum AMH levels during the late night appears not clinically relevant. Co-variation in the levels of LH and AMH might indicate joint regulatory mechanisms for the latter hormone and gonadotrophins.

Preovulatory progesterone concentration associates significantly to follicle number and LH concentration but not to pregnancy rate.

Using data from a large prospective randomized controlled trial that evaluated the effect of recombinant LH (rLH)co-administration for ovarian stimulation, the present study assessed whether progesterone concentration on the day of human chorionic gonadotrophin (HCG) administration was associated with pregnancy outcome. Progesterone concentration was measured on stimulation day 1 and on the day of HCG administration in 475 patients who underwent IVF/intracytoplasmic sperm injection treatment following ovarian stimulation with gonadotrophin-releasing hormone (GnRH) agonist and recombinant FSH with or without rLH administration from day 6 of stimulation. There was no significant association between the late-follicular-phase progesterone concentration and the clinical pregnancy rate. However, progesterone concentration was strongly associated with the number of follicles and retrieved oocytes. Late-follicular-phase LH concentration also showed a significant positive association with progesterone concentration (P = 0.018). Administration of rLH during ovarian stimulation did not affect progesterone concentration. The present study does not support an association between progesterone concentration on the day of HCG administration and the probability of clinical pregnancy in women undergoing ovarian stimulation with GnRH agonists and gonadotrophins for assisted reproduction treatment.Instead, late-follicular-phase progesterone concentration appears to be governed by the number of preovulatory follicles and LH concentration.

What is the optimal luteal support in assisted reproductive technology?

The need for luteal phase support in IVF/ICSI is well established. A large effort has been made in the attempt to identify the optimal type, start, route, dosage and duration of luteal phase support for IVF/ICSI and frozen embryo transfer. These questions are further complicated by the different types of stimulation protocols and ovulation triggers used in ART. The aim of this review is to supply a comprehensive overview of the available types of luteal phase support, and the indications for their use. A review of the literature was carried out in the effort to find the optimal luteal phase support regimen with regards to pregnancy related outcomes and short and long term safety. The results demonstrate that vaginal, intramuscular, subcutaneous and rectal progesterone are equally effective as luteal phase support in IVF/ICSI. GnRH agonists and oral dydrogesterone are new and promising treatment modalities but more research is needed. hCG and estradiol are not recommended for luteal phase support. More research is needed to establish the most optimal luteal phase support in frozen embryo transfer cycles, but progesterone has been shown to improve live birth rate in some studies. Luteal phase support should be commenced between the evening of the day of oocyte retrieval, and day three after oocyte retrieval and it should be continued at least until the day of positive pregnancy test. So, in conclusion still more large and well-designed RCT's are needed to establish the most optimal luteal phase support in each stimulation protocol, and especially in frozen embryo transfer.

Significant Serum Progesterone Variations on the Day of Final Oocyte Maturation in Stimulated IVF Cycles.

Objective: To evaluate intraday serum progesterone levels on the day of final oocyte maturation in women undergoing ovarian stimulation in a GnRH-antagonist protocol. Study design, size, and duration: The study was done as a prospective observational study at a Private IVF centre in Muscat, Oman. 30 patients were recruited from May 2018 to March 2019. Patients: Thirty patients with primary/secondary infertility and an indication for ovarian stimulation for IVF/ICSI treatment. The study was registered at the clinicaltrials.gov under the number: NCT03519776. Main outcome measures: Progesterone levels at 4 time points (8 a.m., 11 a.m., 2 p.m. and 5 p.m.) on the day of final oocyte maturation. Results: A total of 120 samples from 30 patients were included in this prospective study. Progesterone levels on the day of final oocyte maturation showed a significant decline over the day with the mean values at 8 a.m.:1.0 ng/ml, at 11 a.m.:0.8 ng/ml, at 2 a.m.: 0.7 ng/ml and at 5 p.m.:0.6 ng/ml. The difference between the first and the last progesterone level was 0.4 ng/ml, reflecting a 37.8% decline of the progesterone level within 9 h and there was a highly significant decrease in the progesterone levels recorded between 8 a.m. and 11 a.m., between 8 a.m. and 2 p.m., between 8 a.m. and 5 p.m. and 11 a.m. and 5 p.m. (p < 0.001). Conclusion: The study findings have two clinically important conclusions: Firstly, progesterone levels on the day of final oocyte maturation decline significantly from the morning to the afternoon in patients, questioning the reliability of one arbitrarily taken progesterone level regarding the decision to perform a fresh embryo transfer or to cryopreserve the embryos. Secondly, declining progesterone levels 12 h after the last administration of gonadotropins support the theory that enhanced ovarian stimulation at the end of the follicular phase leads to an overload of the capacity of the enzymes metabolizing progesterone further on, therefore resulting in elevated progesterone levels in circulation.

Anti-müllerian hormone levels are associated with live birth rates in ART, but the predictive ability of anti-müllerian hormone is modest.

OBJECTIVES: The aim was to evaluate the association between serum Anti-Müllerian Hormone (AMH) level and cumulative live birth rates (LBR) in patients undergoing their first in vitro fertilization (IVF) treatment cycle, and to compare serum AMH levels with Antral Follicle Count (AFC) and Ovarian Sensitivity Index (OSI) as predictors of live birth. STUDY DESIGN: A prospective cohort study of 454 patients under the age of 40 and with a regular menstrual cycle of 21-35 days, undergoing their first IVF treatment cycles between September 2010 and June 2015. Participants were divided into three groups based on their AMH level, (AMH ≤10, AMH 10-<30 and AMH ≥30 pmol/l). Any difference in AMH-distribution between patients with or without live birth was analyzed using a Mann-Whitney-test, and live birth rates were compared between groups by a chi-squared test for linear trend. The ability of AMH, OSI and AFC as predictors of live birth was assessed by a receiver operating characteristics-analysis and the area under the curve (AUC) was calculated. RESULTS: Patients with live birth had a higher AMH, median (range) 26 [0-137] pmol/l, compared with patients without live birth, AMH 22 [0-154] pmol/l, p = 0.035. Mean live birth rate (SD) was 0.36 (0.48) in the total cohort, 0.26 (0.44) in AMH-group <10, 0.34 (0.48) in AMH-group 10-<30, and 0.41(0.49) in AMH-group ≥30. Thus live birth rates increased with 8% per AMH-group (95% CI: 0.02 -0.14, p = 0.015). The AUC for AFC was 0.56, for AMH 0.57 and for OSI 0.63, respectively. CONCLUSION: AMH concentration in serum is associated with live birth rates after IVF. Our results suggest that both AMH, AFC and OSI have an equal but modest predictive ability in relation to live birth rate.

The Impact of the Biological Variability or Assay Performance on AMH Measurements: A Prospective Cohort Study With AMH Tested on Three Analytical Assay-Platforms.

This study examined longitudinal, age-related and intra-individual variation in Anti-Müllerian Hormone (AMH) in regular menstruating women and correlated the hormonal levels to the antral follicle count (AFC). The impact of variations on an algorithm for calculation of follitropin-dose for ovarian stimulation were also tested. The study was carried out at a fertility clinic of a tertiary university hospital and had a prospective trial design. Twenty-six healthy women not receiving infertility treatment aged 22 to 50 years participated. Blood sampling for hormonal analysis was done every fifth day throughout three consecutive menstrual cycles, AFC was determined with 3-dimentional ultrasound and AMH measured by different assays from Beckman Coulter, Roche and Ansh Labs. Outcome measures were maximum and minimum difference in absolute and relative terms for each study subject during the test-period, coefficient of variation (Cv) for AMH for each cycle and cycle-day and correlation between AMH and AFC. The impact from variable AMH levels on an algorithm calculating follitrophin-delta dose in ovarian stimulation was explored. A significant longitudinal age-independent variation in AMH-levels and coefficient of variation in cycles and cycle days was found. A strong correlation between AMH-levels and AFC was confirmed and a case of significant divergence between assays was seen. Variations in AMH had a significant impact on an algorithm calculated dosage of gonadotrophins in ovarian stimulation. The finding of a substantial longitudinal variation in AMH question one recording being sufficient in quantifying gonadotrophins for ovarian stimulation, decision making and prognostication related to infertility treatment and counseling. Occasionally, commercial assays may fail to recognize specific AMH cleavage-products.

The impact of male overweight on semen quality and outcome of assisted reproduction.

It is well-documented that male overweight and obesity causes endocrine disorders that might diminish the male reproductive capacity; however, reports have been conflicting regarding the influence of male body mass index (BMI) on semen quality and the outcome of assisted reproductive technology (ART). The aim of this study was to investigate whether increased male BMI affects sperm quality and the outcome of assisted reproduction in couples with an overweight or obese man and a non-obese partner. Data was prospectively collected from 612 infertile couples undergoing ART at a Danish fertility center. Self-reported information on paternal height and weight were recorded and BMI was calculated. The men were divided into four BMI categories: underweight BMI < 20 kg m(-2) normal BMI 20-24.9 kg m(-2), overweight BMI 25-29.9 kg m(-2) and obese BMI > 30 kg m(-2). Conventional semen analysis was performed according to the World Health Organization guideline and sperm DNA integrity was analyzed by the Sperm Chromatin Structure Assay (SCSA). No statistically significant effect of male BMI was seen on conventional semen parameters (sperm concentration, total sperm count, seminal volume and motility) or on SCSA-results. Furthermore, the outcome of ART regarding fertilization rate, number of good quality embryos (GQE ), implantation and pregnancy outcome was not influenced by the increasing male BMI.

The circadian variation in Anti-Müllerian hormone in patients with polycystic ovary syndrome differs significantly from normally ovulating women.

OBJECTIVE: [corrected] To improve the biologic understanding of the Polycystic Ovarian Syndrome (PCOS) condition by examining the circadian variation and relationship between Anti Müllerian Hormone (AMH), gonadotropins and ovarian steroids in PCOS patients compared to normally ovulating and menstruating women. By comparing the pattern of co-variation between AMH and Luteinizing Hormone, two compounds closely linked to hyperandrogenism and anovulation in PCOS, the involvement of the Hypothalamic-Pituitary-Ovarian axis in PCOS pathology could be elucidated. PATIENTS: Eight normal-weighted young, anovulatory PCOS-women as study group and ten normal menstruating and ovulating women as controls. INTERVENTIONS: Observational prospective study of the circadian variation in AMH, gonadotropins, sex steroids and androgens in a study and a control group. A circadian profile was performed in each study and control subject during a 24-h period by blood sampling every second hour, starting at 8:00 a.m. and continuing until 8:00 a.m. the following day. RESULTS: Significant differences in hormonal levels were found between the groups, with higher concentrations of AMH, LH and androgens in the PCOS group and lower amounts of FSH and progesterone. A distinct difference in the circadian variation pattern of AMH and LH between PCOS patients and normal controls was seen, with PCOS patients presenting a uniform pattern in serum levels of AMH and LH throughout the study period, without significant nadir late-night values as was seen in the control group. In PCOS women, a significant positive association between LH/ FSH and testosterone was found opposite to controls. MAIN OUTCOME MEASURES: Circadian variation in Anti-Müllerian Hormone, gonadotropins and ovarian steroids and the covariation between them. CONCLUSION: A significant difference in the circadian secretion of LH and AMH in PCOS women compared to normally ovulating women indicate an increased GnRH pulse, creating high and constant LH serum concentrations. A significant co-variation between LH and AMH may suggest LH as a factor involved in the control of AMH secretion.

Sperm chromatin structure assay (SCSA): a tool in diagnosis and treatment of infertility.

Diagnosis of male infertility has mainly been based on the World Health Organization (WHO) manual-based semen parameter's concentration, motility and morphology. It has, however, become apparent that none of these parameters are reliable markers for evaluation of the fertility potential of a couple. A search for better markers has led to an increased focus on sperm chromatin integrity testing in fertility work-up and assisted reproductive techniques. During the last couple of decades, numerous sperm DNA integrity tests have been developed. These are claimed to be characterized by a lower intraindividual variation, less intralaboratory and interlaboratory variation and thus less subjective than the conventional sperm analysis. However, not all the sperm chromatin integrity tests have yet been shown to be of clinical value. So far, the test that has been found to have the most stable clinical threshold values in relation to fertility is the sperm chromatin structure assay (SCSA), a flow cytometric test that measures the susceptibility of sperm DNA to acid-induced DNA denaturation in situ. Sperm DNA fragmentation as measured by SCSA has shown to be an independent predictor of successful pregnancy in first pregnancy planners as well as in couples undergoing intrauterine insemination, and can be used as a tool in investigation, counseling and treatment of involuntary childlessness. More conflicting data exist regarding the role of sperm DNA fragmentation in relation to fertilization, pre-embryo development and pregnancy outcome in in vitro fertilization and intracytoplasmic sperm injection (ICSI).

Polymorphisms in the protein C inhibitor gene in in vitro fertilization failure.

The aim of this study was to determine whether total fertilization failure in human IVF can be partially explained by alterations in the gene that codes for protein C inhibitor. Forty-six men had IVF total fertilization failure and 51 controls with normal fertilization were screened for mutations in the protein C inhibitor gene by direct sequencing. The main finding was that in men involved in total fertilization failure, a heterozygous adenosine/guanine (A/G) base combination in position 1389 (rs2069990) (exon 6) in the protein C inhibitor gene was significantly more common compared with controls (10.9% vs. 0).

A prospective study, using sibling oocytes, examining the effect of 30 seconds versus 90 minutes gamete co-incubation in IVF.

BACKGROUND: Traditionally oocytes have been exposed to sperm overnight, for 16-20 h. This long period of co-incubation, however, has been shown to create problems with high levels of reactive oxygen species (ROS), which may affect embryo viability and cause hardening of the zona pellucida. Recently, a positive effect of reducing the co-incubation time to 90-120 min was reported. The objective of this study was to evaluate whether a further reduction of the co-incubation period could benefit the outcome of IVF. METHODS: In this prospective study, 777 sibling oocytes from 81 women undergoing IVF were divided via alternate allocation to co-incubation for either 30 s (ultrashort co-incubation) (group A) or for 90 min (standard co-incubation) (group B). Endpoints were normal fertilization (two-pronuclear, 2PN), polyspermy (>2PN), embryo quality (EQ), clinical pregnancy (CP) and implantation (IR). RESULTS: The normal fertilization rates of the two groups were comparable: group A 58.6% versus group B 58.0%. Significantly lower rates of polyspermy were seen in group A compared to group B (2.8 versus 7.2%, P = 0.008). No statistically significant differences in EQ, CP or IR were seen. CONCLUSION: This is the first study demonstrating the achievement of good fertilization rates in IVF with ultrashort co-incubation. Significantly lower rates of polyspermy were seen in the group with ultrashort compared to the standard co-incubation group. Further studies are, however, needed in order to evaluate whether ultrashort co-incubation has any effect on the outcome of IVF.

Pain relief during oocyte retrieval--exploring the role of different frequencies of electro-acupuncture.

Electro-acupuncture has previously proven its analgesic effect in oocyte retrieval for IVF. The aim of the present prospective randomized study was to explore the optimal frequency for analgesia when electro-acupuncture was applied a few minutes prior to oocyte retrieval. A total of 152 patients were prospectively randomized to receive either a combination of high (80 Hz) and low frequency (2 Hz), 3 s each, a so-called mixed frequency, or a fixed frequency of 20 Hz during oocyte retrieval. In addition to electro-acupuncture, both groups had a paracervical block and manual acupuncture. No differences in pain before, during or after oocyte retrieval between the two groups were seen. In the fixed frequency group, however, a higher level of anxiety (P < 0.05) before oocyte retrieval was seen, and a higher level of nausea after aspiration of one ovary (P < 0.01) was seen in the mixed frequency group. No differences were seen regarding clinical outcome parameters. Contrary to previous reports on acute and chronic pain, the analgesic effect of the mixed frequency and the fixed frequency was similar when used for short duration electro-acupuncture.

Impact of follicular-fluid meiosis-activating sterol in an albumin-based formulation on the incidence of human pre-embryos with chromosome abnormalities.

OBJECTIVE: To evaluate the effect of adding follicular-fluid meiosis-activating sterol (FF-MAS) in a novel 0.2% recombinant human albumin-based formulation to cumulus-enclosed oocytes on chromosomal status and development of pre-embryos. DESIGN: Multicenter, prospective, randomized, open (double-blind for vehicle and FF-MAS groups), four parallel groups, controlled trial. SETTING: Four public IVF clinics in Denmark. PATIENT(S): Two hundred eighteen women undergoing IVF donated 483 oocytes. INTERVENTION(S): Follicle-stimulating hormone/hCG-primed cumulus-enclosed oocytes randomized to 4 hours of exposure to medium with 1 or 10 micromol/L of FF-MAS dissolved in 0.2% recombinant human albumin, medium with 0.2% recombinant human albumin (vehicle control), or medium alone (control) before insemination. MAIN OUTCOME MEASURE(S): Primary endpoint: incidence of human pre-embryos with chromosomal abnormalities. Secondary endpoint: fertilization rate, cleavage rate, and pre-embryo quality assessed after 68 hours of culture. RESULT(S): At pre-embryo level, the overall abnormality rates in the control, vehicle control, and 1- and 10-micromol/L FF-MAS groups were 53%, 39%, 42%, 53%, respectively, and at blastomere level 49%, 44%, 44%, and 48%, respectively. After 20 and 26 hours, the fertilization rates were between 67% and 71% in all groups. No differences in the cleavage rates were observed. CONCLUSION(S): The concentrations of FF-MAS in a novel 0.2% recombinant human albumin-based formulation of FF-MAS did not increase the risk of chromosomal abnormalities in pre-embryos or blastomeres. No statistically significant differences in fertilization rate, cleavage rate, or number of good quality pre-embryos were found among the four groups.