Background: Arterial hemoglobin oxygen saturation (SaO₂) decreases at an altitude of >1,500 m. There are no reports on normal SaO₂ at altitudes between 0 and 1,500 m. The clinical significance of decreased SaO₂ at such altitudes is unclear. Objective: To test the hypothesis that in healthy volunteers normal SaO₂ at moderate altitude (MA; 725 m) is lower than that at almost sea level (SL; 43 m). Methods: SaO₂ was measured by transcutaneous pulse oximetry in young healthy volunteers at MA and was compared to equivalent measurements at SL. In addition, a 6-min walk test was performed and SaO₂ at the end of the walk was compared between the two locations. Results: 111 males were checked at MA and 101 at SL. At rest, nadir SaO₂ was 95% at MA compared to 97% at SL. Mean SaO₂ at rest was slightly higher at SL (98.53 ± 0.52) compared to MA (98.11 ± 0.8; p < 0.01). In subjects who completed the 6-min walk test, SaO₂ slightly decreased after the test in both locations, by 0.38 ± 0.65% in the SL group and by 0.37 ± 1.12% in the MA group. This difference is not statistically significant by univariate analysis; however, a multiple regression analysis indicated that the drop in SaO₂ was higher at MA than at low altitude. Conclusions: We found a low but significant difference in SaO₂ between near-SL and at an altitude of 725 m. The clinical significance of this difference, in terms of human health, is probably minimal.

Purpose: To compare pregnancy rates in GnRH-antagonist cycles triggered with hCG after luteal phase support with intranasal GnRH agonist as sole luteal phase support versus standard vaginal progesterone preparation. Methods: Prospective randomized controlled study of patients who underwent antagonist-based IVF cycles triggered with hCG at university-affiliated tertiary medical center between 2020 and 2022. Patients meeting the inclusion criteria were randomly assigned to either intranasal GnRH-agonist or vaginal progesterone for luteal phase support. Pregnancy rates were the main outcome compared between the two study groups. Results: A total of 150 patients underwent 164 cycles, 127 cycles of which were included in the study cohort. Of them, 64 (50.4%) and 63 (49.6%) cycles were treated with GnRH-agonist or progesterone respectively as sole luteal phase support. A significantly higher pregnancy rate was demonstrated in the GnRH-agonist group compared with the progesterone group. After adjustment of several potential confounders such as age, body mass index, past obstetric history, number of IVF cycles, oocyte retrieved and embryos transferred, GnRH-agonist was still associated with a higher pregnancy rate (odds ratio 3.4, 95% confidence interval 1.4-8.3). Ovarian hyperstimulation syndrome rates were similar between the groups. Conclusions: This prospective study suggests that nasal GnRH-agonist for luteal phase support is associated with higher pregnancy rates compared with standard progesterone support in an antagonist-based protocol triggered with hCG, while maintaining a similar safety profile.

Purpose: To compare pregnancy rates in GnRH-antagonist cycles triggered with hCG after luteal phase support with intranasal GnRH agonist as sole luteal phase support versus standard vaginal progesterone preparation.Methods: Prospective randomized controlled study of patients who underwent antagonist-based IVF cycles triggered with hCG at university-a liated tertiary medical center between 2020 and 2022. Patients meeting the inclusion criteria were randomly assigned to either intranasal GnRH-agonist or vaginal progesterone for luteal phase support. Pregnancy rates were the main outcome compared between the two study groups.Results: A total of 150 patients underwent 164 cycles, 127 cycles of which were included in the study cohort. Of them, 64 (50.4%) and 63 (49.6%) cycles were treated with GnRH-agonist or progesterone respectively as sole luteal phase support. A signi cantly higher pregnancy rate was demonstrated in the GnRH-agonist group compared with the progesterone group. After adjustment of several potential confounders such as age, body mass index, past obstetric history, number of IVF cycles, oocyte retrieved and embryos transferred, GnRH-agonist was still associated with a higher pregnancy rate (odds ratio 3.4, 95% con dence interval 1.4-8.3). Ovarian hyperstimulation syndrome rates were similar between the groups.Conclusions: This prospective study suggests that nasal GnRH-agonist for luteal phase support is associated with higher pregnancy rates compared with standard progesterone support in an antagonistbased protocol triggered with hCG, while maintaining a similar safety pro le. HighlightsTo the best of our knowledge, this is the rst prospective randomized study to compare between pregnancy rates of patients treated with repeated intranasal GnRH-a versus progesterone as sole LPS following GnRH-ant-based cycles triggered with hCG. Our ndings suggest that intranasal GnRH-a administration as a sole luteal support in antagonist-based IVF cycles triggered with hCG results in improved pregnancy rates in comparison with traditional irritating vaginal preparations, giving ART caregivers another medical option and further personalizing reproductive medicine.

Study question Are pregnancy rates in GnRH-antagonist cycles triggered with hCG and luteal phase support (LPS) with intranasal GnRH-agonist or vaginal progesterone comparable? Summary answer Nasal GnRH-agonist for LPS is associated with higher pregnancy rates compared with standard progesterone support in antagonist-based cycles triggered with hCG What is known already Regardless of its mechanism of action, the use of GnRH-a during the luteal phase in addition to progesterone, either in a single or multiple doses, has become a common practice as a part of ART protocols, based on its association with higher pregnancy and live birth rates . Its use as a sole agent for LPS has not gained the same popularity although studies supporting non-inferiority and even higher live birth rates with GnRH-a as a sole LPS agent have been published. Study design, size, duration A single-center, prospective, randomized study. A total of 150 patients underwent 164 GnRH-antagonist-based IVF cycles triggered with hCG and fresh embryo transfer. The study was conducted between June 9th, 2020, and May 5th, 2022. Participants/materials, setting, methods The study was conducted in the IVF clinic at University-affiliated tertiary medical center. Patients meeting the inclusion criteria who underwent antagonist-based IVF cycles and hCG triggering were enrolled. Computer-based randomization (1:1 ratio) was performed on the day of oocyte pickup (OPU). In both groups LPS was initiated on the evening of the OPU day with either GnRH-agonist nasal spray (Nafareline, nasal spray 200 mcg twice daily)or vaginal micronized progesterone (Utrogestan 300 mg, 3 times daily). Main results and the role of chance A total of 150 patients underwent 164 cycles, 127 cycles of which were included in the study cohort. Of them, 64 (50.4%) and 63 (49.6%) cycles were treated with GnRH-agonist or progesterone respectively as sole luteal phase support. A significantly higher pregnancy rate was found in the GnRH-a group compared with the progesterone group (43.8% versus 25.4% respectively; P = 0.030). After adjustment of several potential confounders such as age, body mass index (BMI), past obstetric history, number of IVF cycles, oocytes retrieved and embryos transferred, GnRH-agonist was still associated with a higher pregnancy rate (odds ratio 3.4, 95% confidence interval 1.4-8.3). Ovarian hyperstimulation syndrome (OHSS) rates were similar between the groups. Significantly higher progesterone levels were measured at β-hCG testing day in the GnRH-a group, both for the cleavage stage embryos (129.1±23.7 nmol/L vs. 97.7±48.9 nmol/L, P = 0.024) and for the blastocysts (127.2±0.1 nmol/L vs. 75.3±49.1 nmol/L, P = 0.034). Limitations, reasons for caution This study is not powered for analysis of clinical pregnancy rates, live birth rates and pregnancy outcomes. Larger studies are needed for research of these outcomes. All patients participating were at low risk for OHSS, therefore the study is underpowered to find significant differences in early or late OHSS.Wider implications of the findings Our findings suggest that intranasal GnRH-agonist administration as a sole luteal support in antagonist-based IVF cycles triggered with hCG results in higher pregnancy rates in comparison with traditional irritating vaginal preparations while not mandating additional support in the first weeks of pregnancy. Trial registration number Clinicaltrials.gov - NCT05484193