Female sex hormones fluctuate in a predictable manner throughout the menstrual cycle in eumenorrheic women. In studies conducted in both animal and humans, estrogen and progesterone have been found to exert individual metabolic effects during both rest and exercise, suggesting that estrogen may cause an increase in fat oxidation during exercise. However, not all studies find these metabolic changes with the natural physiological variation in the sex hormones. To date, no studies have investigated whether whole body peak fat oxidation rate (PFO) and maximal fat oxidation intensity (FATmax) are affected at different time points [mid-follicular (MF), late-follicular (LF), and mid-luteal (ML)] in the menstrual cycle, where plasma estrogen and progesterone are either at their minimum or maximum. We hypothesized that an increased plasma estrogen concentration together with low progesterone concentration in LF would result in a modest but significant increase in PFO. We found no differences in body weight, body composition, or peak oxygen uptake (V̇o2peak) between any of the menstrual phases in the 19 healthy, young eumenorrheic women included in this study. PFO [MF: 0.379 (0.324–0.433) g/min; LF: 0.375 (0.329–0.421) g/min; ML: 0.382 (0.337–0.442) g/min; mean ± (95% CI)] and resting plasma free fatty acid concentrations [MF: 392 (293–492) µmol/l; LF: 477 (324–631) µmol/l; ML: 396 (285–508) µmol/L] were also similar across the menstrual cycle phases. Contrary to our hypothesis, we conclude that the naturally occurring fluctuations in the sex hormones estrogen and progesterone do not affect the whole body PFO and FATmax in young eumenorrheic women measured during a graded exercise test. NEW & NOTEWORTHY Menstrual cycle phase does not affect the peak fat oxidation rate during a graded exercise test. Natural physiological fluctuations in estrogen do not increase peak fat oxidation rate. FATmax is not influenced by menstrual cycle phase in healthy, young eumenorrheic women.
BACKGROUND In Europe, the number of frozen embryo transfer (FET) cycles is steadily increasing, now accounting for more than 190 000 cycles per year. It is standard clinical practice to postpone FET for at least one menstrual cycle following a failed fresh transfer or after a freeze-all cycle. The purpose of this practice is to minimise the possible residual negative effect of ovarian stimulation on the resumption of a normal ovulatory cycle and receptivity of the endometrium. Although elective deferral of FET may unnecessarily delay time to pregnancy, immediate FET may be inefficient in a clinical setting, following an increased risk of irregular ovulatory cycles and the presence of functional cysts, increasing the risk of cycle cancellation. OBJECTIVE AND RATIONALE This review explores the impact of timing of FET in the first cycle (immediate FET) versus the second or subsequent cycle (postponed FET) following a failed fresh transfer or a freeze-all cycle on live birth rate (LBR). Secondary endpoints were implantation, pregnancy and clinical pregnancy rates (CPR) as well as miscarriage rate (MR). SEARCH METHODS We searched PubMed (MEDLINE) and EMBASE databases for MeSH and Emtree terms, as well as text words related to timing of FET, up to March 2020, in English language. There were no limitations regarding year of publication or duration of follow-up. Inclusion criteria were subfertile women aged 18-46 years with any indication for treatment with IVF/ICSI. Studies on oocyte donation were excluded. All original studies were included, except for case reports, study protocols and abstracts only. Covidence, a Cochrane-tool, was used for sorting and screening of literature. Risk of bias was assessed using the Robins-I tool and the quality of evidence using the Grading of Recommendations, Assessment, Development and Evaluation framework. OUTCOMES Out of 4124 search results, 15 studies were included in the review. Studies reporting adjusted odds ratios (aOR) for LBR, CPR and MR were included in meta-analyses. All studies (n = 15) were retrospective cohort studies involving a total of 6,304 immediate FET cycles and 13,851 postponed FET cycles including 8,019 matched controls. Twelve studies of very low to moderate quality reported no difference in LBR with immediate versus postponed FET. Two studies of moderate quality reported a statistically significant increase in LBR with immediate FET and one small study of very low quality reported better LBR with postponed FET. Trends in rates of secondary outcomes followed trends in LBR regarding timing of FET. The meta-analyses showed a significant advantage of immediate FET (n =2,076) compared to postponed FET (n =3,833), with a pooled aOR of 1.20 (95% CI 1.01–1.44) for LBR and a pooled aOR of 1.22 (95% CI 1.07–1.39) for CPR. WIDER IMPLICATIONS The results of this review indicate a slightly higher LBR and CPR in immediate versus postponed FET. Thus, the standard clinical practice of postponing FET for at least one menstrual cycle following a failed fresh transfer or a freeze-all cycle may not be best clinical practice. However, as only retrospective cohort studies were assessed, the presence of selection bias is apparent, and the quality of evidence thus seems low. Randomised controlled trials including data on cancellation rates and reasons for cancellation are highly needed to provide high-grade evidence regarding clinical practice and patient counselling.
Growth differentiation factor 15 (GDF15) is a stress-induced cytokine. Although the exact physiological function of GDF15 is not yet fully comprehended, the significant elevation of circulating GDF15 levels during gestation suggests a potential role for this hormone in pregnancy. This is corroborated by genetic association studies in which GDF15 and the GDF15 receptor, GDNF Family Receptor Alpha Like (GFRAL) have been linked to morning sickness and hyperemesis gravidarum (HG) in humans. Here, we studied GDF15 biology during pregnancy in mice, rats, macaques, and humans. In contrast to macaques and humans, mice and rats exhibited an underwhelming induction in plasma GDF15 levels in response to pregnancy (~75-fold increase in macaques vs. ~2-fold increase in rodents). The changes in circulating GDF15 levels were corroborated by the magnitude of Gdf15 mRNA and GDF15 protein expression in placentae from mice, rats, and macaques. These species-specific findings may help guide future studies focusing on GDF15 in pregnancy and on the evaluation of pharmacological strategies to interfere with GDF15-GFRAL signaling to treat severe nausea and HG.
Introduction Today, it is widespread practice to postpone frozen embryo transfer (FET) in a modified natural cycle (mNC) for at least one menstrual cycle after oocyte retrieval and failed fresh embryo transfer or freeze-all. The rationale behind this practice is the concern that suboptimal ovarian, endometrial or endocrinological conditions following ovarian stimulation may have a negative impact on endometrial receptivity and implantation. However, two recent systematic reviews and meta-analyses based on retrospective data did not support this practice. As unnecessary delay in time to transfer and pregnancy should be avoided, the aim of this study is to investigate if immediate single blastocyst transfer in mNC-FET is non-inferior to standard postponed single blastocyst transfer in mNC-FET in terms of live birth rate. Methods and analysis Multicentre randomised controlled non-blinded trial including 464 normo-ovulatory women aged 18–40 years undergoing single blastocyst mNC-FET after a failed fresh or freeze-all cycle. Participants are randomised 1:1 to either FET in the first menstrual cycle following the stimulated cycle (immediate FET) or FET in the second or subsequent cycle following the stimulated cycle (postponed FET). The study is designed as a non-inferiority trial and primary analyses will be performed as intention to treat and per protocol. Ethics and dissemination Ethical approval has been granted by the Scientific Ethical Committee of the Capital Region of Denmark (J-nr.: H-19086300). Data will be handled according to Danish law on personal data protection in accordance with the general data protection regulation. Participants will complete written consent forms regarding participation in the study and storage of blood samples in a biobank for future research. The study will be monitored by a Good Clinical Practice (GCP)-trained study nurse not otherwise involved in the study. The results of this study will be disseminated by publication in international peer-reviewed scientific journals. Trial registration number NCT04748874; Pre-results.
Study question Do women undergoing mNC-FET with progesterone supplementation experience mental health adverse effects at a greater rate compared to a control group. Summary answer Progesterone supplementation does not affect mental wellbeing in women undergoing mNC-FET. What is known already Women and men undergoing assisted reproductive treatment more likely to experience stress and other adverse psychological effects than the background population. Various factors such as parental age, cause of infertility and treatment method have been shown to affect patient well-being. Progesterone supplementation is known to cause various physical adverse effects, yet few studies have investigated the potential mental health adverse effects of progesterone supplementation in FET. Study design, size, duration This is a sub-study of an ongoing RCT investigating the effect of luteal phase progesterone supplementation in mNC-FET. The aim is to investigate possible mental health adverse effects of progesterone. From 2019–2021 a total of 164 women were included (n = 84 and n = 82 in the progesterone and control group, respectively). The health and wellbeing self-reporting survey was fulfilled after randomization on hCG trigger + 11 days. Participants/materials, setting, methods A validated, electronic questionnaire in Danish was used to measure mental wellbeing in women aged 18–41 years undergoing mNC-FET with and without use of progesterone supplementation in the luteal phase at seven Danish public hospitals. Women were randomized to either progesterone treatment or no progesterone by a computerized randomization algorithm with minimization for female age > =37 years, previous oocyte retrievals and previous FET. Comparisons of survey responses were performed by chi-square tests. Main results and the role of chance The survey response rate was 68%. We observed no significant differences in any of the three items between the progesterone group and the control group. On the first item “to which degree have you felt sensitive due to treatment”, 56% and 52% responded “to a large degree” or “to some degree” sensitive in the progesterone vs. control group, while 25% and 34% vs. 19% and 13% responded “to a lesser extent” or “not at all” sensitive in progesterone vs. controls (P = 0.35). On the second item, “to which degree have you felt aggressive due to treatment”, 10% and 9% responded “to a large degree” or “to some degree”, 29% and 22% answered “to a lesser degree” and 62% and 70% responded “not at all” in the progesterone vs control group (P = 0.57). On the third item “to which degree have you cried unexpectedly due to treatment” 25% and 18% responded “to a large degree” or “to some degree” in the progesterone vs control group, 20% and 27% answered “to a lesser extent”, while 55% in both groups answered “not at all” (P = 0.44). Limitations, reasons for caution In a self-reported survey selection bias, due to a less than 100% response rate, and reporting bias cannot be excluded. However with the possibility to answer the survey online at leisure, the risk of reporting bias is minimized. Wider implications of the findings: A large concern for clinicians working with ART is patient wellbeing. Our study suggests that luteal phase support does not cause extra emotional distress, though further research is needed. Trial registration number NCT03795220
Study question Can frozen embryo transfer (FET) be offered immediately after a stimulated IVF/ICSI cycle without compromising live birth rate (LBR)? Summary answer FET in the menstrual cycle immediately following the stimulated IVF/ICSI cycle was associated with a slightly higher LBR compared to standard postponed FET. What is known already It is standard clinical practice to postpone FET for at least one menstrual cycle following a failed fresh transfer or a freeze-all cycle. This practice is thought to minimize any possible residual negative effect of ovarian stimulation, with excessive steroid levels and multiple corpora lutea, on the resumption of a normal ovulatory cycle and receptivity of the endometrium. Even so, elective deferral of FET is an empirical strategy based on suggestions rather than solid scientific evidence and may unnecessarily delay time to pregnancy, causing frustration and decreased quality of life to couples. Study design, size, duration Systematic review and meta-analysis according to PRISMA guidelines. Original studies on subfertile women aged 18-46 with any indication for treatment with IVF/ICSI investigating the timing of FET after IVF/ICSI were included. Intervention was defined as FET in the menstrual cycle immediately following the stimulated IVF/ICSI cycle. Comparator was defined as FET in the second or subsequent menstrual cycle following IVF/ICSI. Risk of bias was assessed using Robins-I and quality of evidence using GRADE. Participants/materials, setting, methods PubMed (MEDLINE) and EMBASE databases were searched for MeSH and Emtree terms, as well as text words related to timing of FET, up to March 2020. There were no limitations regarding year of publication or duration of follow-up but to English language. The primary outcome was LBR. Secondary outcomes were implantation rate, pregnancy rate, clinical pregnancy rate (CPR), time-to-pregnancy, miscarriage rate (MR), cycle cancellation rate and patient wellbeing. Main results and the role of chance Out of 4124 search results, 15 studies were included in the review. Studies reporting adjusted odds ratios (aOR) for LBR, CPR and MR were included in meta-analyses. All studies (n = 15) were retrospective cohort studies involving a total of 6,304 immediate FET cycles and 13,851 postponed FET cycles including 8,019 matched controls. Twelve studies of very low to moderate quality reported no difference in LBR with immediate versus postponed FET. Two studies of moderate quality reported a statistically significant increase in LBR with immediate FET and one small study of very low quality reported better LBR with postponed FET. Trends in rates of secondary outcomes followed trends in LBR regarding timing of FET. The meta-analyses showed a significant advantage of immediate FET (n = 2,076) compared to postponed FET (n = 3,833), with a pooled aOR of 1.20 (95% CI 1.01-1.44) for LBR and a pooled aOR of 1.22 (95% CI 1.07-1.39) for CPR. Limitations, reasons for caution Limitations include the retrospective design and heterogeneity of studies included, limiting comparison and pooling of data. With little transparency regarding cancellation rates, the risk of selection bias is apparent. Further, confounding by embryo quality is a limitation. Small sample sizes are a limitation to subgroup meta-analyses. Wider implications of the findings The standard clinical practice of postponing FET for at least one menstrual cycle following a failed fresh transfer or a freeze-all cycle may not be best clinical practice. Randomized controlled trials including data on cancellation rates are highly needed to provide high grade evidence regarding clinical practice and patient counseling. Trial registration number not applicable
Study question Can frozen embryo transfer (FET) be offered immediately after a stimulated IVF/ICSI cycle without compromising live birth rate (LBR)? Summary answer FET in the menstrual cycle immediately following the stimulated IVF/ICSI cycle was associated with a slightly higher LBR compared to standard postponed FET. What is known already It is standard clinical practice to postpone FET for at least one menstrual cycle following a failed fresh transfer or a freeze-all cycle. This practice is thought to minimize any possible residual negative effect of ovarian stimulation, with excessive steroid levels and multiple corpora lutea, on the resumption of a normal ovulatory cycle and receptivity of the endometrium. Even so, elective deferral of FET is an empirical strategy based on suggestions rather than solid scientific evidence and may unnecessarily delay time to pregnancy, causing frustration and decreased quality of life to couples. Study design, size, duration Systematic review and meta-analysis according to PRISMA guidelines. Original studies on subfertile women aged 18–46 with any indication for treatment with IVF/ICSI investigating the timing of FET after IVF/ICSI were included. Intervention was defined as FET in the menstrual cycle immediately following the stimulated IVF/ICSI cycle. Comparator was defined as FET in the second or subsequent menstrual cycle following IVF/ICSI. Risk of bias was assessed using Robins-I and quality of evidence using GRADE. Participants/materials, setting, methods PubMed (MEDLINE) and EMBASE databases were searched for MeSH and Emtree terms, as well as text words related to timing of FET, up to March 2020. There were no limitations regarding year of publication or duration of follow-up but to English language. The primary outcome was LBR. Secondary outcomes were implantation rate, pregnancy rate, clinical pregnancy rate (CPR), time-to-pregnancy, miscarriage rate (MR), cycle cancellation rate and patient wellbeing. Main results and the role of chance Out of 4124 search results, 15 studies were included in the review. Studies reporting adjusted odds ratios (aOR) for LBR, CPR and MR were included in meta-analyses. All studies (n = 15) were retrospective cohort studies involving a total of 6,304 immediate FET cycles and 13,851 postponed FET cycles including 8,019 matched controls. Twelve studies of very low to moderate quality reported no difference in LBR with immediate versus postponed FET. Two studies of moderate quality reported a statistically significant increase in LBR with immediate FET and one small study of very low quality reported better LBR with postponed FET. Trends in rates of secondary outcomes followed trends in LBR regarding timing of FET. The meta-analyses showed a significant advantage of immediate FET (n = 2,076) compared to postponed FET (n = 3,833), with a pooled aOR of 1.20 (95% CI 1.01–1.44) for LBR and a pooled aOR of 1.22 (95% CI 1.07–1.39) for CPR. Limitations, reasons for caution: Limitations include the retrospective design and heterogeneity of studies included, limiting comparison and pooling of data. With little transparency regarding cancellation rates, the risk of selection bias is apparent. Further, confounding by embryo quality is a limitation. Small sample sizes are a limitation to subgroup meta-analyses. Wider implications of the findings: The standard clinical practice of postponing FET for at least one menstrual cycle following a failed fresh transfer or a freeze-all cycle may not be best clinical practice. Randomized controlled trials including data on cancellation rates are highly needed to provide high grade evidence regarding clinical practice and patient counseling. Trial registration number Not applicable
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