P–627 Optimal timing of day 6 blastocyst transfer in artificially prepared frozen-thawed embryo transfer cycles

Abstract Study question When is the optimal timing of day 6 (D6) blastocyst transfer between the 6thday (P6)and the 7th(P7) day of progesterone administration in artificially prepared frozen-thawed embryo transfer(FET) cycle Summary answer When transferring D6 blastocysts in artificially prepared FET cycles, live birth rate tended to be higher in P6 group than in P7 group. What is known already Blastocyst transfer in FET cycles has increased due to several reasons including convenience for optimization of endometrial synchronization, improvement of laboratory techniques and preimplantation genetic testing. Meanwhile, D6 blastocyst which cryopreserved on day 6 after being developed to the full blastocyst stage, presented lower pregnancy outcomes in FET cycle than D5 blastocysts. However, there have been few studies on the optimal duration of progesterone administration when transferring D6 blastocysts. Study design, size, duration This was a retrospective cohort study including patients who underwent frozen-thawed blastocyst transfer in artificially prepared cycles from January 2000 to May 2020. Patients with D6 blastocyst transfer on the 6th day of progesterone administration were included in D6-P6 group, and patients with D6 blastocyst transfer on the 7th day of progesterone administration were included in D6-P7 group. Participants/materials, setting, methods Increasing dose of estradiol valerate was administered from the 3rd day of menstruation: 4 mg/day for the first four days, 6 mg/day for next four days, and then 8 mg/day until the confirmation of pregnancy. Progesterone was administered from the 14th day of menstruation if the endometrial thickness reached ≥7 mm. The independent t-test or Mann-Whitney test, chi-square test, and logistic regression analysis were performed. Main results and the role of chance A total of 50 patients were included, and 13 patients underwent FET on P6 and 37 patients underwent FET on P7. Live birth rate was comparable between the P6 group and the P7 group (18.9% vs. 15.4%, p = 0.775). Live birth rate was higher in the D6-P6 group than in the D6-P7 group after adjusting for age, AMH, endometrial thickness on the starting day of progesterone administration and good embryo rate transferred with statistical significance (OR: 6.716, p = 0.005). Limitations, reasons for caution Limitations of the present study is the retrospective design and the small sample size. Caution is needed in extrapolating results of this study because only intramural and vaginal progesterone supplementations were included in this study. Wider implications of the findings: Even if the duration of blastocyst formation was delayed, frozen-thawed D6 blastocyst may need to be considered for on P6 rather than P7. The difference of live birth rate is not statistically significant. This study should be acknowledged for the underestimation of the difference because of the small sample size. Trial registration number Not applicable

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P–335 Endometrial compaction 5–10% is associated with the best live birth rate in artificial frozen-thawed embryo transfer cycles

Human Reproduction ◽

10.1093/humrep/deab130.334 ◽

2021 ◽

Vol 36 (Supplement_1) ◽

Author(s):

E Yaprak ◽

Y E Sukur ◽

B Ozmen ◽

M Sonmezer ◽

B Berker ◽

...

Keyword(s):

Pregnancy Outcome ◽

Embryo Transfer ◽

Live Birth ◽

Birth Rate ◽

Endometrial Thickness ◽

Live Birth Rate ◽

Follicular Phase ◽

Endometrial Preparation ◽

Frozen Thawed Embryo Transfer ◽

Thawed Embryo Transfer

Abstract Study question What is the effect of endometrial compaction on live birth rate in frozen-thawed embryo transfer (FET) cycles? Summary answer In FET cycles with artificial endometrial preparation, the chance for live birth was significantly higher in cycles with endometrial compaction. What is known already Most studies conclude that thinner the endometrium poorer the pregnancy outcome. These studies mostly include measurements in the follicular phase. Since endometrial thickness indicates receptivity, one may expect the endometrial thickness measured on ET day to be more important to predict the outcome. However, few studies assessed endometrial thickness on ET day and unlike follicular phase studies conflicting results were obtained regarding pregnancy outcome. The change in endometrial thickness may be more valuable to predict the pregnancy outcome rather than a single measurement. Study design, size, duration Retrospective observational cohort study. 283 FET cycles in which all patients underwent artificial endometrial preparation were reviewed. Participants/materials, setting, methods: The inclusion criteria were artificial endometrial preparation, age between 20–38 years. The same protocol was applied to all patients for the endometrial preparation.The change of endometrial thickness between the end of estrogen phase and embryo transfer day was recorded. Any decrement is defined as endometrial compaction. The patients were grouped according to the changes of endometrial thicknesses as compaction and non-compaction. Main results and the role of chance Among 283 cycles, 89 had endometrial compaction and 194 did not have compaction. The clinical pregnancy, implantation and live birth rates were significantly higher in the compaction group when compared to non-compaction group (P values 0.007, 0.009, and 0.039, respectively). In order to evaluate the results according to the degree of compaction, we divided the patients into 5% compaction slices. The live birth rate was significantly higher in the 5–10% compaction group (P = 0.016). A multivariable logistic regression analysis was performed to examine the independent effects of different variables on live birth chance.In FET cycles with artificial endometrial preparation, the chance for live birth was significantly higher in cycles with endometrial compaction (OR: 2.352, 95% confidence interval {CI} 1.297–4.264, P = 0.005). A receiver operating characteristic (ROC) curve analysis was performed to evaluate whether there was a certain threshold of endometrial thickness at the end of estrogen phase for endometrial compaction to occur. The sensitivity and specificity of 9.25 mm at the end of estrogen phase calculated from the ROC curve were 76.4% and 58.8%, respectively (area under the curve: 0.701, 95% CI 0.640–0.763; P < 0.001). Limitations, reasons for caution The main limitations of the study were its retrospective nature, relatively small sample size and utilization of different ultrasound techniques at different measurements (using transvaginal ultrasound at the end of the estrogen phase and transabdominal ultrasound on ET day). Wider implications of the findings: Recently a cohort study they found that endometrial compaction results in better pregnancy outcomes, similar to our findings. But, this is the first study to suggest a threshold value (9.2) for endometrial thickness before the commencement of progesterone in regards to increase the chance of compaction. Trial registration number Not applicable

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P–785 Double versus sequential single blastocyst transfer in freeze all cycles?

Human Reproduction ◽

10.1093/humrep/deab130.784 ◽

2021 ◽

Vol 36 (Supplement_1) ◽

Author(s):

S Ertas ◽

B Balaban ◽

B Urman ◽

K Yakin

Keyword(s):

Embryo Transfer ◽

Live Birth ◽

Birth Rate ◽

Live Birth Rate ◽

Small Sample ◽

Blastocyst Transfer ◽

Multiple Birth ◽

Live Births ◽

Single Blastocyst Transfer ◽

Twin Delivery

Abstract Study question Is double blastocysts transfer (DET) better than sequential single blastocyst transfer (seq-SET) in freeze all cycles? Summary answer Sequential single blastocyst transfer provides a higher live birth rate (LBR) per cycle initiated and eliminates multiple births in freeze-all cycles. What is known already Improvements in cryopreservation technology helped freeze-all strategy gain much popularity. The new debate is whether guidance for single embryo transfer should also be applied to frozen-thawed embryo transfers in freeze-all cycles. Study design, size, duration We performed a retrospective cohort analysis of 860 women in whom the entire cohort of embryos frozen at the blastocyst stage for various indications. All women aged 19–43 years, who had at least two blastocysts frozen and subsequently thawed and transferred were included. Preimplantation genetic testing cycles were excluded.The study period ranged from January 2016 to May 2019. Participants/materials, setting, methods Data regarding female age, number of embryos transferred, multiple pregnancy and live birth rates (LBR) were extracted from the electronic database. Women were categorized based on their age and the mode of embryo transfer. Primary outcome was live birth rate LBR per cycle initiated. Secondary outcomes were LBR per embryo transfer and multiple birth rate. Groups were compared using Fisher’s test, generalized estimating equation model and logistic regression analysis to adjust for confounding factors. Main results and the role of chance The study group comprised of 666 women (371 Seq-SET and 295 DET) who underwent 837 embryo transfer cycles. Second embryo transfer was affected in 46.1% of women in the Seq-SET group. Age, indication for freeze-all, and mode of transfer were related with the LBR. For women ≤ 35 (n = 370), LBRs per embryo transfer were similar in single and double embryo transfers (53.9% versus 64.2% respectively, p = 0.006, aOR=0.65, 95% CI:0.41–1.01). However, LBR per cycle initiated was significantly higher in Seq-SET group (78.9% versus 64.2% respectively, p = 0.004, aHR=2.09, 95% CI:1.28–3.41). While only one monochorionic twin delivery was observed with Seq-SET (0.5%), 19 out of 70 (27.1%) live births after DET were twins. For women >35 of age (n = 296) the likelihood of a live birth per embryo transfer was lower in single compared to double embryo transfers (33.2% versus 46.2%, respectively, p = 0.012, aOR=0.58 95% CI:0.38–0.88). Although LBR per cycle initiated was higher in Seq-SET (58.2%) than DET (46.2%), the difference did not reach statistical significance (p = 0.054, aHR=1.62, 95% CI:1.00–2.60). While no twin delivery was observed with Seq-SET, 8 out of 86 (9.3%) live births with DET were twins. Limitations, reasons for caution This was a retrospective study with small sample size performed at a single fertility center, which may limit the generalizability of our findings. Cost-efficiency was not studied. Wider implications of the findings: Seq-SET is associated with a comparable or higher likelihood of live birth per cycle initiated and a very low risk of twins when compared to DET. However, half of SET cases had to undergo two transfer cycles. Trial registration number NA

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P–700 Increased progesterone to mature oocyte index is associated with lower top-quality embryo rate in GnRH antagonist protocols

Human Reproduction ◽

10.1093/humrep/deab130.699 ◽

2021 ◽

Vol 36 (Supplement_1) ◽

Author(s):

Y E Şükür ◽

K Pouya ◽

B Özmen ◽

M Sönmezer ◽

B Berker ◽

...

Keyword(s):

Live Birth ◽

Birth Rate ◽

Embryo Quality ◽

Small Sample Size ◽

Live Birth Rate ◽

Mature Oocyte ◽

Small Sample ◽

University Hospital ◽

Control Group ◽

Study Cohort

Abstract Study question Do progesterone elevation (PE) on trigger day and progesterone to mature oocyte index (PMOI) affect embryo quality and the chance of live birth? Summary answer The top-quality embryo rate is decreased by increasing PMOI, but it has no association with absolute serum progesterone levels. What is known already Progesterone elevation have been reported to significantly decrease pregnancy and implantation rates. The main mechanism of this adverse effect is mainly related to an asynchrony between the endometrium and the embryo. Many of the previous studies have failed to show a significant impact of PE on embryo quality and the success of subsequent frozen-thawed embryo transfer (FET) cycle. However, PMOI was suggested to be more predictive than PE of ART outcome and might be associated with embryo quality. Study design, size, duration A single-centre retrospective cohort study was conducted. All FET cycles performed in a university hospital infertility centre between January 2016 and December 2019 were reviewed. A total of 44 patients who had PE (>1.5 ng/ml) on trigger day and 134 patients who did not have PE were assessed. Participants/materials, setting, methods The study group consisted of patients who had PE (>1.5 ng/mL) during fresh COS cycle and the control group consisted of patients who did not have PE. In addition to effect of PE on subsequent FET cycle outcome, an association between PMOI and embryo quality was assessed. The threshold level to define increased PMOI (>0.12 ng/ml) was calculated as the median level of the whole study cohort. Main results and the role of chance The mean ages of the study and control groups were 30.4±5.4 years and 31.1±5.6 years, respectively (P = 0.413). Although the number of oocytes collected and MII oocytes were significantly higher in patients with PE, the total number of frozen embryos were similar between the groups. There were no significant differences concerning the outcome measures including live birth rate in the subsequent FET cycle between participants with and without PE (27.3% vs. 23.9%, respectively; P = 0.652). The rate of top-quality embryos was similar between participants with and without PE (43% vs. 52%, respectively; P = 0.370). However, the rate of top-quality embryos was significantly lower in cycles with PMOI>0.12 ng/ml than in cycles PMOI<0.12 ng/ml (42% vs. 56%, respectively; P = 0.027). Limitations, reasons for caution The retrospective design and the small sample size derived from a single institution. Wider implications of the findings: Increased PMOI, which is associated to lower top-quality embryo rate, may in turn result in diminished cumulative live birth rate. Trial registration number Not applicable

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Impact of Endometrial Thickness and Volume Compaction on the Live Birth Rate Following Fresh Embryo Transfer of In Vitro Fertilization

Journal of Ultrasound in Medicine ◽

10.1002/jum.15830 ◽

2021 ◽

Author(s):

Mei T. Lam ◽

Hang W. R. Li ◽

Ernest H. Y. Ng

Keyword(s):

In Vitro Fertilization ◽

Embryo Transfer ◽

Live Birth ◽

Birth Rate ◽

Endometrial Thickness ◽

Live Birth Rate ◽

Fresh Embryo Transfer ◽

Vitro Fertilization

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The effect of air bubble position on ART outcome in frozen-thawed blastocyst transfer

10.21203/rs.3.rs-1059586/v1 ◽

2021 ◽

Author(s):

Tingting Yang ◽

Bo Chen ◽

Xiaoyan Sun ◽

Qingyang Li ◽

Qiumei Li ◽

...

Keyword(s):

Pregnancy Rate ◽

Live Birth ◽

Birth Rate ◽

Live Birth Rate ◽

Clinical Pregnancy ◽

Clinical Pregnancy Rate ◽

Blastocyst Transfer ◽

Ultrasound Guided ◽

Air Bubble ◽

Art Outcome

Abstract Background So far, only few literatures have studied the relationship between blastocyst transfer position and ART outcomes, and the conclusions are still controversial. Our study is to evaluate the effect of air bubble position on ART outcome and to find the optimal embryo transfer position in frozen-thawed blastocyst transfer. Methods This study included a retrospective cohort analysis of 399 frozen-thawed single blastocyst transfers ultrasound-guided performed between June 1, 2017 and November 30, 2020. All of the women scheduled for frozen-thawed single blastocyst transfers ultrasound-guided. The primary outcome is clinical pregnancy rate and the secondary outcome is live birth rate. Statistical analyses were conducted using One-way Anova, Kruscal Whallis H test, chi-square test and Smooth curve fitting. Results When BFD was less than 19 mm, there was no significant change in clinical pregnancy rate as BFD increased (OR = 0.95, 95% CI: 0.89 to 1.02, P = 0.1373); when BFD was more than 19 mm, the clinical pregnancy rate decreased by 16% for every 1 mm increase in BFD (OR = 0.84, 95% CI: 0.72 to 0.98, P = 0.0363). The effect of BFD on live birth rate were similar to that on clinical pregnancy rate, the inflection point was 19mm, when BFD was more than 19 mm, the live birth rate decreases by 58% for every 1 mm increase in BFD (OR = 0.42, 95% CI: 0.21 to 0.86, P = 0.0174) Conclusions The ideal pregnancy outcome can be achieved within 19mm from uterus fundus after single blastocyst transfer, The clinical pregnancy and live birth at a distance of more 19mm from the uterus fundus have a cliff-like downward trend.

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P–304 The endometrial preparation protocol does not affect the live-birth-rate after vitrified-warmed euploid single blastocyst transfers: an analysis of 1884 procedures

Human Reproduction ◽

10.1093/humrep/deab130.303 ◽

2021 ◽

Vol 36 (Supplement_1) ◽

Author(s):

C Petriglia ◽

A Vaiarelli ◽

D Cimadomo ◽

C Gentile ◽

F Fiorini ◽

...

Keyword(s):

Live Birth ◽

Gestational Age ◽

Birth Rate ◽

Live Birth Rate ◽

Blastocyst Transfer ◽

Workload Management ◽

Endometrial Preparation ◽

Blastocyst Quality ◽

The Impact ◽

Micronized Progesterone

Abstract Study question Is the live-birth-rate (LBR) different when comparing artificial (AC) and modified-natural (M-NC) cycle for endometrial preparation to vitrified-warmed euploid blastocyst transfer? Summary answer The LBR after vitrified-warmed euploid blastocyst transfer seem independent of the endometrial preparation administered. What is known already Only the transfer of a competent embryo on a receptive endometrium might result in successful implantation. Three main protocols for endometrial preparation to vitrified-warmed embryo transfer exist: NC, M-NC, and AC. None among them, though, has been shown more appropriate than the others to date, especially since, only in a few studies, the analysis was restricted to single euploid blastocyst transfers to limit the impact of embryonic issues on implantation. In conclusion, no clear consensus exists and the choice is still largely based on menstrual/ovarian cycle characteristics and patient’s needs. Study design, size, duration All first vitrified-warmed single euploid blastocyst transfers performed between April–2013 and March–2020 were included in the analysis. Endometrial preparation was conducted with either an AC (N = 1211) or a M-NC (N = 673). The protocol was chosen based on patients’ logistical reasons. The primary outcome was the LBR per transfer. Sub-analyses based on blastocyst quality and day of development were conducted. Birthweight, gestational age, gestational and perinatal issues were secondary outcomes. Participants/materials, setting, methods AC: oral estradiol-valerate 3-times/day from day2–3 of the cycle until the endometrial thickness reached ≥7mm, then 600 mg/day of micronized progesterone. The transfer was conducted on day6 of progesterone administration. M-NC: an intramuscular dose of 10,000IU hCG was administrated when the leading follicle was >17 mm and the endometrium was thicker than 7mm and trilaminar, plus 400 mg/day of micronized-progesterone as luteal phase support starting 36–40hr post-hCG. The transfer was conducted on day7 after trigger. Main results and the role of chance The two groups were similar for maternal age at retrieval (38.0±3.3yr) and transfer (38.3±3.3yr), reproductive history, embryological outcomes of the IVF cycle, body-mass-index, basal hormonal levels, and blastocyst features (Gardner’s classification: AA = 73%, AB/BA=11%, BB/AC/CA=8%, CC/BC/CB=8%; day5=48%, day6=47%, day7=5%). The LBR was 46.7% (N = 565/1211) and 49.9% (N = 336/673) after AC and M-NC, respectively, resulting in an odds-ratio 1.14, 95%CI:0.94–1.37. The absence of significant differences was confirmed also when adjusted for blastocyst quality and day of full-development (1.16, 95%CI:0.96–1.41). Among the 565 and 336 deliveries, the birthweight was similar (3290.3±470.7 versus 3251.7±521.5 g, Mann-Whitney-U-test=0.5), the gestational age was similar (38.5±1.7 versus 38.4±1.9 weeks, Mann-Whitney-U-test=0.5). Also, the rates of newborns who were normal (81% versus 82%), large (8% versus 9%), and small (11% versus 9%) for gestational age were similar (Chi-squared-test=0.5). The rates of patients experiencing gestational (6% versus 7%) and/or perinatal issues (3% versus 3%) were also similar (Fisher’s-exact-tests=0.4). Limitations, reasons for caution This is a retrospective study conducted in poor prognosis patients indicated to preimplantation genetic testing for aneuploidies. Future randomized controlled trials and cost-effectiveness analysis are desirable, as well as studies in different patient populations. Lastly, each gestational/perinatal issue shall be analyzed per se (e.g. different placentation disorders). Wider implications of the findings: The absence of clinical and perinatal differences between the two protocols for endometrial preparation supports the adoption, whenever needed, of AC. This approach, in fact, allows a higher flexibility in patients’ and daily workload management. Trial registration number None

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Influence of surgical evacuation on pregnancy outcomes of subsequent embryo transfer cycle following miscarriage in an initial IVF cycle: a retrospective cohort study

BMC Pregnancy and Childbirth ◽

10.1186/s12884-019-2543-9 ◽

2019 ◽

Vol 19 (1) ◽

Author(s):

Junan Meng ◽

Mengchen Zhu ◽

Wenjuan Shen ◽

Xiaomin Huang ◽

Haixiang Sun ◽

...

Keyword(s):

Embryo Transfer ◽

Live Birth ◽

Pregnancy Outcomes ◽

Birth Rate ◽

Endometrial Thickness ◽

Live Birth Rate ◽

First Trimester ◽

Miscarriage Rate ◽

Significant Difference ◽

Surgical Evacuation

Abstract Background It is still uncertain whether surgical evacuation adversely affects subsequent embryo transfer. The present study aims to assess the influence of surgical evacuation on the pregnancy outcomes of subsequent embryo transfer cycle following first trimester miscarriage in an initial in vitro fertilization and embryo transfer (IVF-ET) cycle. Methods A total of 645 patients who underwent their first trimester miscarriage in an initial IVF cycle between January 2013 and May 2016 in Nanjing Drum Tower Hospital were enrolled. Surgical evacuation was performed when the products of conception were retained more than 8 h after medical evacuation. Characteristics and pregnancy outcomes were compared between surgical evacuation patients and no surgical evacuation patients. The pregnancy outcomes following surgical evacuation were further compared between patients with ≥ 8 mm or < 8 mm endometrial thickness (EMT), and with the different EMT changes. Results The EMT in the subsequent embryo transfer cycle of surgical evacuation group was much thinner when compared with that in the no surgical evacuation group (9.0 ± 1.6 mm vs. 9.4 ± 1.9 mm, P = 0.01). There was no significant difference in implantation rate, clinical pregnancy rate, live birth rate or miscarriage rate between surgical evacuation group and no surgical evacuation group (P > 0.05). The live birth rate was higher in EMT ≥ 8 mm group when compared to < 8 mm group in surgical evacuation patients (43.0% vs. 17.4%, P < 0.05). Conclusions There was no significant difference in the pregnancy outcomes of subsequent embryo transfer cycle between surgical evacuation patients and no surgical evacuation patients. Surgical evacuation led to the decrease of EMT, especially when the EMT < 8 mm was association with a lower live birth rate.

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BLACK RACE RESULTS IN LOWER LIVE BIRTH RATE (LBR) IN FROZEN-THAWED BLASTOCYST TRANSFER CYCLES (FET): AN ANALYSIS OF 7,002 SART FET CYCLES

Fertility and Sterility ◽

10.1016/j.fertnstert.2020.08.163 ◽

2020 ◽

Vol 114 (3) ◽

pp. e51-e52

Author(s):

Reeva B. Makhijani ◽

Alicia Y. Christy ◽

Prachi N. Godiwala ◽

Kim L. Thornton ◽

Daniel R. Grow ◽

...

Keyword(s):

Live Birth ◽

Birth Rate ◽

Live Birth Rate ◽

Blastocyst Transfer ◽

Black Race

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Progesterone Intramuscularly or Vaginally Administration May Not Change Live Birth Rate or Neonatal Outcomes in Artificial Frozen-Thawed Embryo Transfer Cycles

Frontiers in Endocrinology ◽

10.3389/fendo.2020.539427 ◽

2020 ◽

Vol 11 ◽

Author(s):

Yuan Liu ◽

Yu Wu

Keyword(s):

Preterm Delivery ◽

Live Birth ◽

Birth Rate ◽

Live Birth Rate ◽

Neonatal Outcomes ◽

Progesterone Level ◽

Delivery Rate ◽

Serum Progesterone ◽

Frozen Thawed Embryo Transfer ◽

Thawed Embryo Transfer

BackgroundsPrevious studies suggested that singletons from frozen-thawed embryo transfer (FET) were associated with higher risk of large, post-date babies and adverse obstetrical outcomes compared to fresh transfer and natural pregnancy. No data available revealed whether the adverse perinatal outcomes were associated with aberrantly high progesterone level from different endometrium preparations in HRT-FET cycle. This study aimed to compare the impact of progesterone intramuscularly and vaginally regimens on neonatal outcomes in HRT-FET cycles.MethodsA total of 856 HRT-FET cycles from a fertility center from 2015 to 2018 were retrospectively analyzed. All patients had their first FET with two cleavage-staged embryos transferred. Endometrial preparation was performed with sequential administration of estrogen followed by progesterone intramuscularly 60 mg per day or vaginal gel Crinone 90 mg per day. Pregnancy outcomes including live birth rate, singleton birthweight, large for gestational age (LGA) rate, small for gestational age (SGA) rate, and preterm delivery rate were analyzed. Student’s t test, Mann-Whitney U-test, Chi square analysis, and multivariable logistic regression were used where appropriate. Differences were considered significant if p < 0.05.ResultsNo significant difference of live birth rate was found between different progesterone regimens (Adjusted OR 1.128, 95% CI 0.842, 1.511, p = 0.420). Neonatal outcomes like singleton birthweight (p = 0.744), preterm delivery rate (Adjusted OR 1.920, 95% CI 0.603, 6.11, p = 0.269), SGA (Adjusted OR 0.227, 95% CI 0.027, 1.934, p = 0.175), and LGA rate (Adjusted OR 0.862, 95% CI 0.425, 1.749, p=0.681) were not different between two progesterone regimens. Serum P level >41.82 pmol/L at 14 day post-FET was associated with higher live birth rate than serum P level ≤41.82 pmol/L in HRT-FET cycles when progesterone was intramuscularly delivered (Adjusted OR 1.690, 95% CI 1.002, 2.849, p = 0.049). But singleton birthweight, preterm delivery rate, SGA and LGA rate were not different between these two groups.ConclusionsRelatively higher serum progesterone level induced by intramuscular regimen did not change live birth rate or neonatal outcomes compared to vaginal regimen. Monitoring serum progesterone level and optimizing progesterone dose of intramuscular progesterone as needed in HRT-FET cycles has a role in improving live birth rate without impact on neonatal outcomes.

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