O-290 Cumulative live birth rates in a freeze-all and fresh transfer strategy after one complete ART cycle in ovulatory women

Study question

Is the cumulative live birth rate(CLBR) similar following a freeze-all and fresh transfer strategy including nearly all subsequent frozen-thaw cycles from the same oocyte retrieval?

Summary answer

The chance of at least one live birth after use off all fresh and frozen blastocysts is similar following a freeze-all and fresh transfer strategy

What is known already

Traditionally, ART success rates have been reported as pregnancies per fresh cycle or per embryo transfer. Advancements such as blastocyst culture and vitrification have enhanced survival and improved live birth rates. This facilitates single blastocyst transfer, a steadily increasing use of vitrified-warmed transfers, and a growing implementation of elective freeze-all cycles worldwide. Hence CLBRs, defined as the proportion of deliveries with at least one live birth following the use of all fresh and frozen embryos derived from one ovarian stimulation cycle, constitutes a better measure of IVF treatment success providing an all-inclusive success rate for ART.

Study design, size, duration

CLBR was a secondary outcome in a multicentre randomised trial with allocation 1:1 to (A) Freeze-all strategy involving GnRH agonist trigger and single vitrified-warmed blastocyst transfer in consecutive modified-natural FET cycles or (B) Fresh transfer strategy with hCG trigger and fresh single blastocyst transfer followed by consecutive single blastocyst FET cycles. The minimum follow-up time from the start of ovarian stimulation was 2 years.

Participants/materials, setting, methods

460 women initiating their 1.,2. or 3. ART cycle at eight different clinics in Denmark, Sweden and Spain. The GnRH antagonist protocol and modified-natural frozen-thaw cycles with single blastocyst transfer were applied. Cumulative live birth was defined as at least one live birth per woman after all fresh and/or frozen cycles from a single ovarian stimulation. Women were followed until the first live birth. Analyses were performed according to the ITT principle.

Main results and the role of chance

Baseline and treatment-related characteristics were similar between the two groups and a similar proportion of women had additional frozen-thawed embryo transfers following the initial fresh or frozen transfer. Combining all fresh and/or frozen transfers from the included oocyte retrieval with a minimum of 2-years of follow-up, the cumulative live birth rate was 42.6% (95/223) in the freeze-all group versus 41.7% (96/230) in the fresh transfer strategy group (risk ratio (RR): 1.0; 95%CI 0.87-1.19, P = 0.93). The median (IQR) time to first pregnancy was 106.0 (80.5-156.5) versus 29.0 (27.0-113.5) days in the Freeze all and Fresh transfer group, respectively. Of all subsequent frozen transfers, a total of 34/103 (33%) cycles resulted in a live birth in the freeze all group compared with 29/108 (26.9%) in the fresh transfer group (risk ratio (RR): 1.09; 95% CI 0.91-1.3; P = 0.41). Finally, a total of three (1.3%) and eight (3.5%) blastocysts in the freeze all and fresh transfer strategy group respectively, did not survive the freezing thawing process (p = 0.24). The number of women with unused cryopreserved embryos at the end of the 2-year follow-up period was four (0.9%) in the freeze all and seven (1.6%) in the fresh transfer group.

Limitations, reasons for caution

The primary RCT outcome was ongoing pregnancy rate following two treatment strategies within the ART regimen hence two different ovulation trigger modalities were applied, introducing a risk of bias. Furthermore, despite a 2-year follow-up few women (2.4%) still had cryopreserved embryos and no live birth at the end of follow-up.

Wider implications of the findings

Advancements of embryo culture and freezing-thawing techniques facilitate an elective single embryo transfer policy. CLBRs provide an all-inclusive success rate for ART. A freeze-all strategy can be used as an alternative to a fresh transfer strategy in women at risk of OHSS as CLBRs are similar.

Trial registration number

NCT02746562

O-126 Impact of letrozole cO-treatment during ovarian stimulation on the oocyte yield, embryo development, and live birth rate – a randomised controlled trial (RIOT)

Study question

Does letrozole co-treatment during ovarian stimulation for in vitro fertilization (IVF) impact oocyte yield, embryo development, and live birth rate (LBR) in expected normal responders?

Summary answer

Letrozole co-treatment leads to similar oocyte yield, embryo- development and utilisation rate, and live birth rate after transfer in the fresh cycle.

What is known already

Letrozole reduces oestradiol levels by inhibiting the aromatization of androgens, this diminishes pituitary suppression and increases endogenous gonadotrophin release. These effects are utilized in ovulation induction in PCOS patients and may benefit certain patients during IVF treatment. In addition, we have recently reported in an RCT that co-treatment with letrozole increases luteal phase progesterone levels and, consistent with previous studies, no significant effect on pregnancy rates was observed. However, the impact of the changes in the endocrine milieu caused by letrozole co-treatment on the developing oocytes and embryos remains unclear as most published studies are retrospective and lack appropriate control-groups.

Study design, size, duration

A multicentre double-blinded randomised placebo-controlled trial was conducted in four fertility clinics at University Hospitals in Denmark from August 2016 to November 2018. 159 women were randomised, 129 women received single embryo (cleavage stage or blastocyst) transfer in the fresh cycle, and the surplus 257 embryos were vitrified. The study was conducted following the Helsinki Declaration and the ICH-Good-Clinical-Practice. Data collection and reporting followed the guidelines of CONSORT to achieve transparent reporting of trials.

Participants/materials, setting, methods

Women with expected normal ovarian response received an antagonist protocol with fixed-dose FSH. Co-treatment consisted of 5mg letrozole or placebo from the start of stimulation until the day of triggering final oocyte maturation with hCG. Standardized morphological evaluation was performed at all centres (applying the Istanbul consensus and Gardner-score). A sub-cohort of the embryos were cultured in an EmbryoScope incubator and further assessed by morphokinetic annotation and reported with.KIDScoreD3. Ongoing pregnancies were followed until birth.

Main results and the role of chance

A total of 1268 oocytes were retrieved from 154 women, leading to development of 386 usable embryos that were either transferred or vitrified. Utilisation rate (the proportion of usable embryos to oocytes) was similar in the letrozole group and placebo group with 0.31 vs. 0.36 (mean difference (MD): -0.05, 95% CI[-0.03;0.12], P = 0.25). Morphologically grading the embryos as “good”, “fair”, and “poor” quality showed similar results, the odds of having a higher quality were 0.78 times higher in the letrozole- vs. placebo group (CI[0.5;1.1], P = 0.2). Morphokinetic annotations (n = 302 embryos) showed similar results with the odds of having a high KIDScore3 1.3 times higher in the letrozole – vs. placebo group (CI[0.9;2.1], P = 0.2). The endometrial thickness at transfer was thinner in the letrozole compared to the placebo group with 8.5 vs. 9.5 mm (MD 1.0, 95% CI[0.4;1.6], P = 0.001) but with the same ultrasonic echogenicity and a preovulatory three-layer appearance. After embryo transfer in the fresh cycle (n = 129), no differences were seen in the pregnancy outcomes: positive serum hCG, ongoing pregnancy rate, early miscarriage rate, foetal miscarriage rate, or LBR. LBR per initiated cycle were similar as well (n = 159): 23.8% vs. 29.1% (MD of -5,3%, CI[-20.3%;9.6%], P = 0.48) in letrozole vs. placebo group, respectively.

Limitations, reasons for caution

Four clinics participating could lead to interobserver variability. However, bias was reduced by block-randomised design. All data are derived from an RCT, the primary endpoint of which, preovulatory progesterone, was the basis of the sample size calculation. The study may have been underpowered to show a significant impact on LBR.

Wider implications of the findings

Letrozole co-treatment during ovarian stimulation with gonadotrophins did not have an impact on the oocyte yield and embryo development. These data suggest that letrozole co-treatment is unlikely to compromise outcomes in its growing indications: ovulation induction, IVF in poor responders, and fertility preservation in breast cancer patients.

Trial registration number

NCT02946684

O-229 Impact of letrozole co-treatment during ovarian stimulation with gonadotropins for in vitro fertilisation (IVF): a multicentre, randomised, double-blinded placebo-controlled trial

Study question

Does reducing estradiol levels with letrozole co-treatment during ovarian stimulation with gonadotropins for IVF impact endocrinological and reproductive outcome markers in expected normal responders?

Summary answer

Letrozole co-treatment maintained follicular phase physiological serum estradiol levels, increased gonadotropin and androgen levels, and increased progesterone in the luteal phase.

What is known already

Ovarian stimulation for IVF causes supraphysiologic estradiol levels, which exert pituitary suppression reducing gonadotropin stimulation of the corpus luteum. Furthermore, stimulation may increase progesterone in the late follicular phase, reported to impair clinical outcomes, through a putative effect on endometrial maturation and embryo-endometrial asynchrony. Co-treatment with the highly selective aromatase inhibitor letrozole during ovarian stimulation has been shown to reduce estradiol levels and FSH consumption in poor responders, but conflicting data in relation to oocyte yield and implantation rates. The impact of letrozole co-treatment on hormonal changes and reproductive outcome after co-treatment in normal responders remains to be clarified.

Study design, size, duration

A multicentre double-blinded randomised placebo-controlled trial conducted in 4 fertility clinics at university hospitals in Denmark from August 2016 to November 2018. 159 women were randomised and 129 completed the study; 67 women in the letrozole group and 62 women in the placebo group. The study was conducted in accordance with the Helsinki Declaration and the ICH-Good-Clinical-Practice. Data collection and reporting followed the guidelines of CONSORT to achieve transparent reporting of trials.

Participants/materials, setting, methods

Women with expected normal ovarian reserve received an antagonist IVF protocol with fixed-dose FSH and fresh single embryo transfer. Co-treatment consisted of once-daily 5 mg letrozole or placebo from the start of stimulation until the day of triggering final oocyte maturation with human chorionic gonadotropin. Serum was collected on 7 visits from stimulation start to 8 days after oocyte retrieval. Clinical pregnancy was determined with a viable foetus by vaginal ultrasound at gestational week 7.

Main results and the role of chance

The proportion of patients with progesterone >1.5 ng/ml in the late follicular phase was similar in the letrozole versus placebo group with 6% versus 0%, respectively (OR 0, 95 % CI [0;1.6], P =.12). Mid-luteal progesterone levels >30 ng/ml were observed in 59% versus 31%, respectively, of subjects in the letrozole and placebo group (OR 3.3, 95% CI [1.4;7.1], P =.005). Letrozole treatment decreased estradiol levels by 69% (95 % CI [60%;75%], P <.0001) and increased luteinizing hormone (LH), testosterone, and androstenedione levels significantly in both the follicular and luteal phase. Follicle-stimulating hormone (FSH) concentration was elevated in the letrozole group at stimulation day 5 and at trigger day, and overall FSH consumption was diminished. The ongoing pregnancy rate did not differ between the letrozole and placebo group (31% versus 39% (risk-difference of 8%, 95% CI [-25%;11%], P =.55). Letrozole had no significant additional side effects apart from those frequently seen during ovarian stimulation, though a trend towards less nausea and vomiting was observed in the letrozole co-treated group versus the placebo group (28% versus 44% (risk-difference of 16%, 95% CI [-2%;33%], P =.11).

Limitations, reasons for caution

The diurnal variation of progesterone has been confirmed since this study was completed, hence the timing of the blood samples was not standardized . However, bias is unlikely due to the randomized design. The study was not powered to show an effect on ongoing pregnancy rates.

Wider implications of the findings

Letrozole co-treatment during ovarian stimulation with gonadotropins maintained serum estradiol at physiological levels, increased follicular phase levels of gonadotropins and androgens, and luteal progesterone levels. These data indicate that letrozole co-treatment may ameliorate the detrimental impacts of gonadotropin stimulation during IVF in normal responders.

Trial registration number

NCT02939898 and NCT02946684

Effects of an induced molt using cassava meal on body weight loss, blood physiology, ovarian regression, and postmolt egg production in late-phase laying hens

This study was conducted to determine the effect of an induced molt using cassava meal on body weight, blood physiology, ovary, and postmolt performance in late-phase (74 wk old) H&N Brown laying hens. Hens were randomly assigned to 3 treatments of 90 birds each: 1) Controls withno induced molt (CONT); 2) molted by full feeding with cassava meal for 3 wk (FP3); and 3) molted by full feeding with cassava meal for 4 wk (FP4). Groups 2 and 3 were fed a pullet developer diet for 3 wk following treatment. During the molt period, the birds were exposed to an 8L:16D photoperiod and had access to drinking water at all times. Thereafter, all hens were fed a layer diet (17%CP), and exposed to a 16L:8D photoperiod, and production performance was measured for 16 wk. The molt treatments resulted in total cessation of egg production within 2 wk following feeding the molt diet. BW loss of birds in the FP4 treatment was approximately 30.13%, which was significantly higher than those in the FP3 treatment (25.23%). At the termination of feeding the molt diet, an increase in hematocrit values was observed for the FP3 and FP4 treatments compared to the CONT treatment. Conversely, lower values of serum estradiol, progesterone, ionized Ca and phosphorus concentrations were found for the 2 molted treatments. Ovary weight, number of follicles, and oviduct weight and length of the FP3 and FP4 treatments were diminished as compared to the CONT treatment. No consistent differences were observed between the molted treatments. Significant (P < 0.05) improvements in postmolt feed efficiency, egg production, Haugh units, shell weight, shell thickness, shell breaking strength, and mortality rate were observed for the FP4 treatment. An improvement in those performances, except for feed efficiency and egg production, was also found for the FP3 treatment. It was concluded that feeding the cassava molt diet for 4 wk could induce molt in laying hens effectively, and produce optimum postmolt productive performance.