Additional progesterone administration during the luteal phase enhances reproductive outcomes in Hormone Replacement Therapy Frozen Embryo Transfer (HRT-FET) cycles in patients with low serum progesterone (P4). In this study we wanted to explore the use of urine P4 as a diagnostic tool during the luteal phase. This prospective observational cohort included a total of 464 HRT-FET cycles. The protocol entailed oral oestradiol (6 mg/24 h), followed by vaginal micronised progesterone (400 mg/12 h). On the day of blastocyst transfer, urine and serum samples were collected. Urine samples were analysed using an ARCHITECT automated immunoassay. A significant difference was found in median urine P4 between patients with serum P4 higher or lower than 11 ng/mL: 6400 ng/mL IQR [2528; 11,930] vs. 3408 ng/mL IQR [592; 6688], p < 0.001. The optimal cut-off to achieve live birth was a urine P4 ≥ 4000 ng/mL. The live birth rate was significantly higher in patients with urine P4 ≥ 4000 ng/mL, 48% (107/222) vs. 35% (45/130), respectively (p = 0.013). The odds ratio for live birth was 1.8 in patients with urine P4 ≥ 4000 ng/mL, 95% CI [1.067; 3.018], p = 0.028. The findings of the present study suggest that urine progesterone could be a valuable diagnostic tool to evaluate the need for additional progesterone in HRT-FET cycles.

To investigate baseline parameters and vaginal intimate hygiene habits comparing IVF patients with and without vaginal dysbiosis, a cross-sectional study. Patients were grouped by the presence of vaginal dysbiosis status determined by a qPCR method (high quantities of Gardnerella spp. and/or Fannyhessea vaginae) and a 16S rRNA gene sequencing-based method (VALENCIA). Patients were asked to fill out a questionnaire alongside an interview with healthcare personnel. Prevalence ratios (PR) were computed in case of statistically significant findings between groups. Among 1511 patients, the prevalence of vaginal dysbiosis by qPCR was 34

The primary aim of the present randomised, double-blind, placebo-controlled trial was to investigate whether clindamycin and live Lactobacillus crispatus CTV-05 (LACTIN-V) would improve clinical pregnancy rates in IVF patients with abnormal vaginal microbiota (AVM) defined by high quantitative PCR loads of Fannyhessea vaginae and Gardnerella spp. IVF patients were randomised prior to embryo transfer into three parallel groups 1:1:1. Group one (CLLA) received clindamycin 300 mg ×2 daily for 7 days followed by vaginal LACTIN-V until the day of pregnancy scan. Group two (CLPL) received clindamycin and placebo LACTIN-V, and finally, group three (PLPL) received an identical placebo of both drugs. A total of 1533 patients were screened, and 338 patients were randomised. The clinical pregnancy rates per embryo transfer were 42% (95%CI 32-52%), 46% (95%CI 36-56%) and 45% (95%CI 35-56%) in the CLLA, CLPL, PLPL groups respectively. Thus, treatment of AVM did not improve reproductive outcome. The EudraCT (European Union Drug Regulating Authorities Clinical Trials Database) clinical trial identifier is 2016-002385-31; first registration day 2016-07-11.

Studies have suggested transferring Day 6 (D6) vitrified blastocyst in a frozen embryo transfer (FET) cycle. This study investigates whether D6 blastocysts should be transferred on the 5th or 6th day of progesterone administration during a hormonal replacement therapy (HRT) FET cycle. A cohort of 746 vitrified D6 single blastocyst HRT-FET cycles was examined in a public Fertility Clinic. Of these, 576 blastocysts were transferred on the 6th day of progesterone (2013-2021), and 170 on the 5th day (2021-2022). The primary outcome was live birth rate (LBR), secondary outcomes were biochemical pregnancy rate (PR), clinical pregnancy rate (CPR), and early pregnancy loss rate (EPLR). No significant differences in LBR, PR, CPR and EPLR were observed, between transfer on the 5th vs. the 6th day of progesterone (23.5% vs. 25.7%, p = 0.76, 38.8% vs. 41.2%, p = 0.61, 26.0% vs. 29.5%, p = 0.40 and 33.3% vs. 28.3%, p = 0.45, respectively). There was no significant difference in basic characteristics and top-quality blastocyst transfers. The timing of D6 vitrified blastocyst transferred on the 5th or the 6th day of progesterone administration in HRT-FET cycles did not significantly impact reproductive outcomes.

ObjectiveTo study whether mid-luteal serum estradiol (E2) levels are associated with the Live Birth Rate in Hormone Replacement Therapy FET cycles in patients with optimal mid-luteal serum progesterone (P4) levels.DesignObservational prospective cohort study of 412 women having a Hormone Replacement Therapy FET single blastocyst transfer from January 2020 to November 2022.SubjectsThe Hormone Replacement Therapy FET priming regimen included oral estradiol (6mg/24h) administered in the evening, followed by vaginal progesterone (400mg/12h). Serum E2 and P4 levels were measured in a standardized manner, 2-4 hours after the latest progesterone administration and 9-14 hours after estradiol administration on the day of blastocyst transfer, day 6 of progesterone administration. Patients with serum P4 <11ng/mL (35nmol/l) on the day of transfer received additional rectal progesterone (400mg/12h). No additional estradiol was administered.Main Outcome MeasuresThe primary outcome was Live Birth Rate in relation to E2 levels at blastocyst transfer day.ResultsThe optimal serum E2 range correlating with ongoing pregnancy was ≥292pg/ml <409pg/ml (≥1070pmol/l and <1500pmol/l). The Live Birth Rate was 59% (60/102) if E2 levels were within this range, whereas a significantly lower Live Birth Rate of 39% (101/260, p=0.001) was seen in patients if E2 levels were <292pg/ml (<1070pmol/l), and of 28% (14/50, p<0.001) if E2 levels were ≥409pg/ml (≥1500pg/mL). In a logistic regression analysis, adjusting for serum progesterone level ≥11ng/mL or <11ng/mL (≥35nmol or <35nmol/l) on the day of transfer, BMI, age at oocyte retrieval, day 5 or 6 vitrified blastocyst and blastocyst score, the adjusted risk difference (RD) of a live birth was -0.21 [-0.32; -0.10] when the E2 level was <292pg/mL (<1070pmol/l) and -0.31 [-0.45; -0.18] if the E2 level was ≥409pg/ml (≥1500pmol/l) compared to E2 levels ≥292pg/ml <409pg/ml (≥1070 <1500pmol/l). Importantly, only 25% of patents had optimal levels.ConclusionThe study shows a significant association between serum E2 levels and reproductive outcomes in a Hormone Replacement Therapy FET cohort in which optimal serum progesterone levels were secured. Mid-luteal serum E2 levels are associated with Live Birth Rate in Hormone Replacement Therapy FET cycles and E2 levels should neither be too high nor too low.

Endometriosis and adenomyosis are distinct clinical conditions that carry the same pathophysiological features. In recent years the clinical focus on assisted reproductive technology patients with either condition (E/A) has increased, in the recognition that this subgroup of patients might need special attention to obtain reproductive success. Endometriosis and adenomyosis are characterized by a disruption of progesterone and oestrogen signalling pathways, resulting in local oestrogen dominance and progesterone resistance at the receptor level. Recent scientific evidence suggests that the endometrial progesterone receptor resistance encountered in E/A patients can be overcome by a freeze-all policy, followed by down-regulating circulating oestradiol concentrations prior to frozen embryo transfer (FET), in combination with an increase in exogenous luteal phase progesterone supplementation in hormonal replacement therapy (HRT) FET cycles. Specifically, for adenomyosis patients who do not respond to gonadotrophin-releasing hormone agonist down-regulation in terms of a decrease in circulating oestradiol concentrations, a small case series has suggested that the addition of an aromatase inhibitor for 21 days prior to HRT-FET is a valid option. Endometriosis and adenomyosis are hormonally active diseases, which need to be treated by controlling local hyperoestrogenism and progesterone resistance. Based on physiology and recent preliminary clinical data, the authors of this opinion paper wish to stimulate discussion and spark interest in research in E/A patients.

Research questionAre serum progesterone levels on the day of modified natural cycle (mNC) frozen blastocyst transfer (FET) without luteal phase support (LPS) associated with clinical pregnancy rate (CPR)?DesignData was collected between January 2019 and October 2022 as a sub-study of an ongoing randomised controlled trial (RCT) assessing pregnancy outcomes in mNC-FET. The sub-study included all women (N=209) randomized to mNC-FET without LPS at the time of data extraction. Participants were aged 18-41 years, had regular menstrual cycles, and underwent mNC-FET treatment with single blastocyst transfer. Associations between serum progesterone level on day of blastocyst transfer and CPR, pregnancy rate (PR), and pregnancy loss rate (PLR) was examined between groups with low and higher progesterone levels using the 25th and the 10th percentiles as cut-offs. Multivariate logistic regression analyses were performed to adjust for potential confounding factors.ResultsProgesterone levels on the day of blastocyst transfer in mNC-FET without LPS ranged from 4.9-91.8 nmol/L, with the 25th and 10th percentile at 29.0 nmol/L and 22.5 nmol/L, respectively. Serum levels of progesterone did not differ between women with or without a clinical pregnancy (mean (SD): 38.5 (14.0) vs 36.8 (12.4) nmol/L, p=0.350). Further, the CPR, PR and PLR were similar in women with low or high progesterone levels when using the 25th or the 10th progesterone percentile as cut-off. Multivariate regression analyses showed no association between progesterone levels and CPR.ConclusionWe found no association between progesterone levels on the day of blastocyst transfer and pregnancy outcome in women undergoing mNC-FET without progesterone LPS.

Introduction This study compares rectal administration with vaginal administration of progesterone as luteal phase support in hormone replacement therapy frozen embryo transfer (HRT-FET) cycles. The reason for comparing the two routes of administration is that rectal administration has been suggested to be more patient friendly.Methods and analysis This study is a randomised controlled trial comparing the ongoing pregnancy rate (OPR) at week 12 in HRT-FET cycles after rectal administered progesterone as the only administered progesterone compared with a vaginal luteal phase support regimen. All patients are enrolled from a Danish public fertility clinic and randomised to one of two groups, with 305 patients receiving embryo transfer assigned to each group. Endometrial preparation includes 6 mg oestradiol daily. The intervention group receives rectally administered progesterone (400 mg/12 hours) and the control group receives vaginally administered progesterone (400 mg/12 hours). If P4 is <35 nmol/L on blastocyst transfer day an additional rectal luteal phase rescue regimen is started (control group). Thawing and transferring of a single autologous vitrified blastocyst is scheduled on the sixth day of progesterone administration in both groups. The power calculation is based on a non-inferiority analysis with an expected OPR in both groups of 44% and the upper limit of a one-sided 95% CI will exclude a difference in favour of the control group of more than 10.0%. An interim analysis will be conducted once half of the study population has been enrolled.Ethics and dissemination The trial was approved on 21 November 2023 by the Danish National Ethical Committee and the Danish Medicines Agency and is authorised by the Clinical Trials Information System (EUCT number 2023-504616-15-02). All patients will provide informed consent before being enrolled in the study. The results will be published in an international journal.Trial registration number EUCT number: 2023-504616-15-02.

Abstract Study question Does subcutaneous (SC) progesterone treatment provide progesterone levels comparable to intramuscular (IM) progesterone when using a cut-off level of 118nmol/l(37.1ng/ml) during intensive luteal phase support? Summary answer As part of an intensive luteal phase support regimen SC progesterone provides higher P4 levels compared to the use of IM progesterone. What is known already Low serum progesterone (P4) levels in HRT-FET cycles negatively impact reproductive outcomes. This effect is particularly pronounced in patients with endometriosis and adenomyosis, due to reduced progesterone actions and progesterone resistance at the receptor level. Therefore, higher serum P4 levels are required to maintain an optimal reproductive outcome during HRT-FET. A P4 cut-off of 118nmol/l (37.1ng/ml) or above has been suggested, a level four times higher than that of the non-endometriosis patient. To achieve high P4 levels, intensive luteal phase support (LPS) regimen has been suggested. This includes vaginal progesterone administration and additional treatment via IM, SC or rectal administration. Study design, size, duration This cohort study includes 380 HRT-FET cycles in endometriosis/adenomyosis patients. Patients were treated from January 2016 until August 2019 with one type of intensive LPS regimen (n = 262) and from January 2000 to January 2023 with two different LPS regimens depending on whether serum P4 levels were lower or higher than 118nmol/l on the day of blastocyst transfer (BT) (n = 118). P4 was measured in a standardised manner. Participants/materials, setting, methods Patients received treatment in a public university affiliated fertility clinic. Endometrial priming involved the use of estradiol followed by vaginal progesterone. From the fourth day of progesterone, one of the following intensive LPS regimens were added: A) 50mg IM progesterone, B) 25mg SC progesterone BD, or C) 25mg SC progesterone BD plus 400mg rectal rescue progesterone BD if P4<118nmol/l. Blastocyst transfer (BT) and P4 measurement were performed on the sixth day of progesterone administration. Main results and the role of chance The overall pregnancy rate, live birth rate (LBR) and total pregnancy loss rates for the whole cohort were 63%, 41% and 36%, respectively. For the three groups A, B and C the mean serum P4 levels on the day of BT were 103.1 ±44.4nmol/l, 170.5 ±62.9nmol/l and 90.1 ±21.5nmol/l. In Group A (IM) 67% of patients (176/262) had P4 levels <118 nmol/l whereas only 36% (43/118; p < 0.001) had P4 <118 nmol/l in the groups of patients treated with SC progesterone (Group B and C). The unadjusted LBR was not significantly different between groups, 39%, 39%, 51%, (p = 0.32). However, a sub-group analysis showed that comparing patients with serum P4 levels <118nmol/l on the BT day in Group A with patients with P4 levels <118nmol/l in Group C a significantly higher LBR was found if intensive LPS included both SC and rectally administered progesterone compared to IM progesterone, only: 51% (44/86) vs 34% (59/176), p = 0.03. The adjusted odds ratio for live birth was 2.04 (95% CI [1.00, 4.16], p = 0.05) after adjusting for age, vitrification day 5 or 6, blastocyst quality and numbers of blastocysts transferred, if intensive LPS included SC and rectal rescue compared to IM, only in patients with P4 levels <118nmol/l. Limitations, reasons for caution This cohort study was conducted over two different time periods. Single embryo transfer was performed only during the later period. The bio-pharmacological profiles of SC and IM progesterone differ, which can influence serum P4 levels. However, in the present study, all blood samples were collected in a standardised manner. Wider implications of the findings This study is the first to report reproductive outcomes following different intensive LPS regimens in a cohort of endometriosis/adenomyosis patients. To increase reproductive outcomes, individualisation of the HRT-FET cycle may be beneficial and, importantly, rectal progesterone administration can be used as a rescue regimen in addition to SC progesterone. Trial registration number Due to the retrospective study design no ethical approval was needed.

(Abstracted from Reprod Biomed Online 2024;49(1):article 103862) With advances in in vitro fertilization (IVF) techniques, it has become safe and efficient to vitrify and warm embryos, and frozen embryo transfer (FET) now has comparable outcomes compared with fresh embryo transfer. A common approach to endometrial preparation for FET is hormone replacement therapy, and because women do not develop a corpus luteum when undergoing hormone replacement therapy–FET, finding an optimal concentration of progesterone is of great clinical interest.

A mid-luteal serum progesterone concentration below 9-11 ng/ml has been shown to have a negative impact on reproductive outcomes in hormone replacement therapy frozen embryo transfer (HRT-FET), and as no corpus luteum is present, this concentration reflects the absorption of the progesterone products administered. However, the composition and dosing regimens of vaginal products vary. In total, 24 studies were included in this review, selected according to the following criteria: the use of vaginal progesterone products, with serum progesterone concentration and regimens reported; the absence of additional progesterone or progestin treatments; and the use of both prospective and retrospective study designs. Abstracts and full texts published in languages other than English were excluded. A random-effects proportional meta-analysis of five different vaginal micronized progesterone products was performed, including a total of 11,014 patients. Significant differences were found when comparing Cyclogest (800 mg) with Crinone (180 mg or 270 mg) (P = 0.01); Cyclogest (800 mg) with Utrogestan/Progestan (600 mg or 800 mg) (P = 0.03); and Cyclogest (800 mg) with Lutinus (300 mg) (P = 0.01). However, no significant differences were identified between products with an equivalent daily dose. In conclusion, significant differences in serum progesterone concentration exist between different vaginal progesterone products and dosing regimens, which must be taken into account when performing HRT-FET.

Research question: Are serum progesterone concentrations on the day of modi fi ed natural cycle (mNC) frozen blastocyst transfer (FET) without luteal phase support (LPS) associated with clinical pregnancy rate (CPR)? Design: Data were collected between January 2019 and October 2022 as a sub -study of an ongoing randomized controlled trial assessing pregnancy outcomes in mNC-FET. The sub -study included all women ( n = 209) randomized to mNC-FET without LPS at the time of data extraction. Participants were aged 18 - 41 years, had regular menstrual cycles and underwent mNC-FET treatment with single-blastocyst transfer. Associations between the serum progesterone concentration on the day of blastocyst transfer and CPR, pregnancy rate and pregnancy loss rate (PLR) were examined between groups with low and higher progesterone concentrations using the 25th and 10th percentiles as cut-offs. Multivariate logistic regression analyses were performed to adjust for potential confounding factors. Results: Progesterone concentrations on the day of blastocyst transfer in mNC-FET without LPS ranged from 4.9 to 91.8 nmol/l, with the 25th and 10th percentiles at 29.0 nmol/l and 22.5 nmol/l, respectively. Serum progesterone concentrations did not differ between women with or without a clinical pregnancy (mean [SD] 38.5 [14.0] versus 36.8 [12.4] nmol/l; P = 0.350). Furthermore, the CPR, pregancy rate and PLR were similar in women with low or high progesterone concentrations when using the 25th or the 10th progesterone percentile as cut-off. Multivariate regression analyses showed no association between progesterone concentrations and CPR. Conclusions: No association was found between progesterone concentration on the day of blastocyst transfer and pregnancy outcome in women undergoing mNC-FET without progesterone LPS.

Abstract Background The serum progesterone (P4) level during the luteal phase (LP) plays a crucial role in the initiation and maintenance of pregnancy. However, it is unclear whether the natural cycle consistently provides the best endocrine profile and whether mid-luteal serum P4 levels are always sufficient to support implantation and early pregnancy. The question has become more relevant in relation to fertility treatment, as more frozen embryo transfer cycles are performed in the natural cycle. Moreover, can serum hormone levels and covariates measured during the follicular phase (FP), such as Follicle Stimulation Hormone (FSH), Luteinizing Hormone (LH), Estradiol (E2), Anti-Mullerian Hormone (AMH) and Antral Follicle Count (AFC), be used to predict P4 levels during the luteal phase (LP)? Results This observational prospective cohort study analysed 26 healthy women with a cycle length between 21–35 days and a body mass index (BMI) < 30 kg/m2. Blood sampling started on the fifth day of the menstrual cycle and continued every fifth day until the next cycle. The procedure was repeated for a total of three cycles. The study found that only ten women had a P4 level greater than 30 nmol/L on cycle day 20 or 25 in all three cycles. In total, only 45 cycles out of 77 cycles had serum P4 levels ≥ 30 nmol/L. The E2 level ≥ 345 pmol/L on cycle day 10 proved to be predictive of a P4 level of ≥ 30 nmol/L on either day 20 or day 25 with a sensitivity of 57% and a specificity of 89%. No other covariates, including the FSH level cycle day 5, LH levels during the follicular phase, age, weight, AFC and AMH cycle day 5 correlated with LP P4 levels. Conclusions A significant correlation between FP E2 levels cycle day 5 (> 131pmol/L) and cycle day 10 (> 345pmol/L) and a LP P4 level ≥ 30 nmol/l was found; thus, the FP E2 level is a predictor of corpus luteum competence. Our findings highlight the existence of suboptimal P4 levels during the LP and a significant inter-individual and intra-cycle variation in P4 levels during the LP in regular menstruating women.

STUDY QUESTION Are there any differences in physical and psychosocial well-being among women undergoing modified natural cycle frozen embryo transfer (mNC-FET) with or without vaginal progesterone as luteal phase support (LPS)? SUMMARY ANSWER Women undergoing mNC-FET with vaginal progesterone supplementation were more likely to experience physical discomfort but there was no difference in psychosocial well-being between the two groups. WHAT IS KNOWN ALREADY mNC-FET can be carried out with or without vaginal progesterone as LPS, which has several side-effects. It is commonly known that fertility treatment can cause stress and psychosocial strain, however, most studies on this subject are conducted in fresh cycle regimes, which differ from NC-FET and results may not be comparable. STUDY DESIGN, SIZE, DURATION This is a sub-study of an ongoing RCT investigating whether progesterone supplementation has a positive effect on live birth rate in mNC-FET. The RCT is conducted at eight fertility clinics in Denmark from 2019 and is planned to end primo 2024. The sub-study is based on two questionnaires on physical and psychosocial well-being added to the RCT in August 2019. On the time of data extraction 286 women had answered both questionnaires. PARTICIPANTS/MATERIALS, SETTING, METHODS Women who had answered both questionnaires were included in the sub-study. Participants were equally distributed, with 143 in each of the two groups. Participants in both groups received the same questionnaires at two time-points: on cycle day 2-5 (baseline) and after blastocyst transfer. Participants in the progesterone group had administered progesterone for 7 days upon answering the second questionnaire. All items in the questionnaires were validated. Items on psychosocial well-being originate from the Copenhagen Multi-Centre Psychosocial Infertility-Fertility Problem Stress Scale (COMPI-FPSS) and from the Mental Health Inventory-5. MAIN RESULTS AND THE ROLE OF CHANCE Women receiving progesterone experienced more vaginal itching and/or burning than women in the non-progesterone group (P < 0.001). Women in the progesterone group also experienced more self-reported vaginal yeast infection, this was, however, not significant after adjustment for multiple testing (P/adjusted P = 0.049/0.881). No differences regarding psychosocial well-being were found between the two groups. Within the progesterone group, a shift toward feeling less 'downhearted and blue' was found when comparing response distribution at baseline and after blastocyst transfer (P < 0.001). LIMITATIONS, REASONS FOR CAUTION All items on physical symptoms were self-reported. The item on vaginal yeast infection was therefore not diagnosed by a doctor. Inclusion in the study required a few extra visits to the clinic, participants who felt more burdened by fertility treatment might have been more likely to decline participation. Women who experienced a lot of side-effects to progesterone prior to this FET cycle, might be less likely to participate. WIDER IMPLICATIONS OF THE FINDINGS Our results are in line with previous known side-effects to progesterone. Physical side-effects of progesterone should be considered before administration. STUDY FUNDING/COMPETING INTEREST(S) The RCT is fully supported by Rigshospitalet's Research Foundation and a grant from Gedeon Richter. Gedeon Richter were not involved in the design of protocol nor in the conduction of the study or analysis of results. A.P., L.P., and N.I.-C.F. report grants from Gedeon Richter, Ferring and Merck with no relations to this study. N.I.-C.F. has received travel support from Ferring, Merck A/S, & Gideon Richter, and is the head of the steering committee for the Danish Fertility Guidelines made by the members of from the Danish Fertility Society. A.P. reports consulting fees from Preglem, Novo Nordisk, Ferring, Gedeon Richter, Cryos, & Merck A/S, honoraria from Gedeon Richter, Ferring, Merck A/S, Theramex, and Organon, has received travel support from Gedeon Richter (payment to institution), participated on an advisory board for Preglem and was loaned an embryoscope from Gedeon Richter to their institution. A.L.S. has stock options for Novo Nordisk B A/S. B.A. have received unrestricted grant from Gedeon Richter Nordic and Merck and honoraria for lectures from Gedeon Richter, Merck, IBSA, and Marckyrl Pharma. TRIAL REGISTRATION NUMBER The RCT is registered on ClinicalTrials. gov (NCT03795220) and in EudraCT (2018-002207-34).

Research questionWhat is the optimal serum progesterone cut-off level in patients with endometriosis undergoing hormone replacement therapy frozen embryo transfer (HRT-FET) with intensive progesterone luteal phase support?DesignA cohort study, including 262 HRT-FET cycles in 179 patients all diagnosed with endometriosis either by laparoscopy or by ultrasound in patients with visible endometriomas. Pre-treatment consisted of 42 days of oral contraceptive pills and 5 days' wash-out, followed by 6 mg oral oestrogen daily. Exogenous progesterone supplementation with vaginal progesterone gel 90 mg/12h commenced when the endometrium was 7 mm or thicker. From the fourth day of vaginal progesterone supplementation, patients also received intramuscular progesterone 50 mg daily. Blastocyst transfer was scheduled for the sixth day of progesterone supplementation.ResultsThe overall positive HCG, live birth (LBR) and total pregnancy loss rates were 60%, 39% and 34%, respectively. The optimal progesterone cut-off level was 118 nmol/l (37.1 ng/ml) defined as the maximum of the Youden index. The unadjusted LBR was significantly higher in patients with progesterone measuring 118 nmol/l or above compared with patients with progesterone measuring less than 118 nmol/l (51% [44/86] versus 34% [59/176], P = 0.01), whereas the adjusted odds ratio for a live birth was 2.1 (95% CI 1.2 to 3.7) after adjusting for age, body mass index, blastocyst score, blastocyst age, quality and number of blastocysts transferred.ConclusionsSerum progesterone levels above 118 nmol/l (37.1ng/ml) resulted in significantly higher LBR compared with lower serum progesterone levels, suggesting that a threshold for optimal serum progesterone exists.

Abstract Study question What are the intimate hygiene practices of women in IVF treatment and do they correlate with the vaginal microbiota? Summary answer Hygiene practices, in specific douching and use of intimate soap significantly increased the risk of abnormal vaginal microbiota (AVM). What is known already The normal vaginal microbiota acts as a defense system against infection. AVM is a molecularly defined vaginal dysbiosis, resembling bacterial vaginosis (BV) and is dominated by anaerobic bacteria such as Gardnerella vaginalis. Importantly, AVM is associated with an increased risk of genital tract infections, poor IVF outcomes, early miscarriage and preterm labor. The cause of AVM is multifactorial and hygiene practices may interrupt the normal microbiota. Previous small studies suggested vaginal douching to be associated with an increased risk of AVM. Few studies have investigated the possible correlation between intimate hygiene practices, menstrual practices and the vaginal microbiota. Study design, size, duration Observational cohort study, including a total of 1421 IVF patients from four Danish fertility centers. The inclusion period was from 2017 to January 2022. Participants/materials, setting, methods Patients aged 18-42 years and undergoing their first, second or third IVF stimulation cycle were eligible for inclusion. The intimate hygiene practices in terms of type of soap, menstrual protection, douching and probiotics, were reported in a structured questionnaire including a total of 40 questions. Vaginal swabs were obtained prior to ovarian stimulation and subsequently subjected to quantitative PCR testing, targeting DNA of dysbiotic bacteria. Main results and the role of chance AVM was present in a total of 34 % (479/1421) of women, and 20% (272/1384) reported vaginal douching, which significantly correlated with AVM (p < 0.01, OR = 1.62 [1.23-2.12]). Intimate soap was used by 39 % (535/1384) of patients, which also significantly increased the risk of AVM ( P = 0.04, OR = 1.35 [1.08-1.69]). Water only was used by 36% (492/1384), and regular soap was used by 27% (374/1384). No correlation between use of water only and regular soap and AVM was detected. For menstrual protection 40% (433/1078) used pads, followed by tampons alone 25% (265/1078) or a combination 21% (230/1078), and 14 % (148/1078) used a menstrual cup. A trend for an increased risk of AVM when using tampons, OR 1.21 [0.91-1.62] was seen whereas use of a menstrual cup seemed to lower the risk of AVM, OR 0.71 [0.48-1.04] Active smoking, higher BMI, drinking >7 units per week and previous chlamydia infection significantly correlated with AVM (p = 0.01, p = 0.01, p = 0.04 and p = 0.01). Finally, 84% (1190/1421) reported gynecological symptoms such as vaginal discharge, dyspareunia and fungal infection, but only fishy odor significantly correlated with AVM (p < 0.01). Limitations, reasons for caution To the best of our knowledge, this is the largest study investigating the intimate hygiene practice and its correlation with AVM in an IVF population. As these results describe the practices of a Scandinavian IVF population, results may differ from other settings and ethnicities. Wider implications of the findings Exploration of the cause-and-effect relations between intimate hygiene practices and AVM is needed, requiring intervention-based prospective studies. This would lead to evidence-based advice on intimate hygiene practices and AVM prevention, possibly increasing live birth rates. The unexpected high prevalence of douching in a Danish IVF population needs further exploration. Trial registration number NCT03420859

The aim of the present randomised, double-blind, placebo-controlled trial was to investigate whether antibiotics and live lactobacilli would improve clinical pregnancy rates in IVF patients with abnormal vaginal microbiota (AVM) defined by high quantitative PCR loads of Fannyhessea vaginae and Gardnerella spp. IVF patients were randomised prior to embryo transfer into three parallel groups 1:1:1. Group one (CLLA) received clindamycin 300 mg ×2 daily for 7 days followed by vaginal Lactobacillus crispatus until the day of pregnancy scan, using the investigational drug LACTIN-V. Group two (CLPL) received clindamycin and placebo LACTIN-V, and finally, group three (PLPL) received an identical placebo of both drugs. A total of 1533 patients were screened, and 338 patients were randomised. The clinical pregnancy rate per embryo transfer was 42% (95%CI 32-52%), 46% (95%CI 36-56%) and 45% (95%CI 35-56%) in the CLLA, CLPL, PLPL groups respectively. Thus, treatment of AVM does not improve reproductive outcome. The EudraCT (European Union Drug Regulating Authorities Clinical Trials Database) clinical trial identifier is 2016-002385-31; first registration day 2016-07-11.