Temperature of embryo culture for assisted reproduction

BACKGROUND: 'Infertility' is defined as the failure to achieve pregnancy after 12 months or more of regular unprotected sexual intercourse. One in six couples experience a delay in becoming pregnant. In vitro fertilisation (IVF) is one of the assisted reproductive techniques used to enable couples to achieve a live birth. One of the processes involved in IVF is embryo culture in an incubator, where a stable environment is created and maintained. The incubators are set at approximately 37°C, which is based on the human core body temperature, although several studies have shown that this temperature may in fact be lower in the female reproductive tract and that this could be beneficial. In this review we have included randomised controlled trials which compared different temperatures of embryo culture. OBJECTIVES: To assess different temperatures of embryo culture for human assisted reproduction, which may lead to higher live birth rates. SEARCH METHODS: We searched the following databases and trial registers: the Cochrane Gynaecology and Fertility (CGF) Group Specialised Register of Controlled Trials, the Cochrane Central Register of Studies Online, MEDLINE, Embase, PsycINFO, CINAHL, clinicaltrials.gov, The World Health Organization International Trials Registry Platform search portal, DARE, Web of Knowledge, OpenGrey, LILACS database, PubMed and Google Scholar. Furthermore, we manually searched the references of relevant articles and contacted experts in the field to obtain additional data. We did not restrict the search by language or publication status. We performed the last search on 6 March 2019. SELECTION CRITERIA: Two review authors independently screened the titles and abstracts of articles retrieved by the search. Full texts of potentially eligible randomised controlled trials (RCTs) were obtained and screened. We included all RCTs which compared different temperatures of embryo culture in IVF or intracytoplasmic sperm injection (ICSI), with a minimum difference in temperature between the two incubators of ≥ 0.5°C. The search process is shown in the PRISMA flow chart. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trial eligibility and risk of bias and extracted data from the included studies; the third review author resolved any disagreements. We contacted trial authors to provide additional data. The primary review outcomes were live birth and miscarriage. Clinical pregnancy, ongoing pregnancy, multiple pregnancy and adverse events were secondary outcomes. All extracted data were dichotomous outcomes, and odds ratios (OR) were calculated with 95% confidence intervals (CIs) on an intention-to-treat basis. We assessed the overall quality of the evidence for the main comparisons using GRADE methods. MAIN RESULTS: We included three RCTs, with a total of 563 women, that compared incubation of embryos at 37.0°C or 37.1°C with a lower incubator temperature (37.0°C versus 36.6°C, 37.1°C versus 36.0°C, 37.0° versus 36.5°C). Live birth, miscarriage, clinical pregnancy, ongoing pregnancy and multiple pregnancy were reported. After additional information from the authors, we confirmed one study as having no adverse events; the other two studies did not report adverse events. We did not perform a meta-analysis as there were not enough studies included per outcome. Live birth was not graded since there were no data of interest available. The evidence for the primary outcome, miscarriage, was of very low quality. The evidence for the secondary outcomes, clinical pregnancy, ongoing pregnancy and multiple pregnancy was also of very low quality. We downgraded the evidence because of high risk of bias (for performance bias) and imprecision due to limited included studies and wide CIs.Only one study reported the primary outcome, live birth (n = 52). They performed randomisation at the level of oocytes and not per woman, and used a paired design whereby two embryos, one from 36.0°C and one from 37.0°C, were transferred. The data from this study were not interpretable in a meaningful way and therefore not presented. Only one study reported miscarriage. We are uncertain whether incubation at a lower temperature decreases the miscarriage (odds ratio (OR) 0.90, 95% CI 0.52 to 1.55; 1 study, N = 412; very low-quality evidence).Of the two studies that reported clinical pregnancy, only one of them performed randomisation per woman. We are uncertain whether a lower temperature improves clinical pregnancy compared to 37°C for embryo incubation (OR 1.08, 95% CI 0.73 to 1.60; 1 study, N = 412; very low-quality evidence). For the outcome, ongoing pregnancy, we are uncertain if a lower temperature is better than 37°C (OR 1.10, 95% CI 0.75 to 1.62; 1 study, N = 412; very low quality-evidence). Multiple pregnancy was reported by two studies, one of which used a paired design, which made it impossible to report the data per temperature. We are uncertain if a temperature lower than 37°C reduces multiple pregnancy (OR 0.80, 95% CI 0.31 to 2.07; 1 study, N = 412; very low-quality evidence). There was insufficient evidence to make a conclusion regarding adverse events, as no studies reported data suitable for analysis. AUTHORS' CONCLUSIONS: This review evaluated different temperatures for embryo culture during IVF. There is a lack of evidence for the majority of outcomes in this review. Based on very low-quality evidence, we are uncertain if incubating at a lower temperature than 37°C improves pregnancy outcomes. More RCTs are needed for comparing different temperatures of embryo culture which require reporting of clinical outcomes as live birth, miscarriage, clinical pregnancy and adverse events

Double versus single intrauterine insemination (IUI) in stimulated cycles for subfertile couples

BACKGROUND: In subfertile couples, couples who have tried to conceive for at least one year, intrauterine insemination (IUI) with ovarian hyperstimulation (OH) is one of the treatment modalities that can be offered. When IUI is performed a second IUI in the same cycle might add to the chances of conceiving. In a previous update of this review in 2010 it was shown that double IUI increases pregnancy rates when compared to single IUI. Since 2010, different clinical trials have been published with differing conclusions about whether double IUI increases pregnancy rates compared to single IUI. OBJECTIVES: To determine the effectiveness and safety of double intrauterine insemination (IUI) compared to single IUI in stimulated cycles for subfertile couples. SEARCH METHODS: We searched the Cochrane Gynaecology and Fertility (CGF) Group trials register, CENTRAL, MEDLINE, Embase and CINAHL in July 2020 and LILACS, Google scholar and Epistemonikos in February 2021, together with reference checking and contact with study authors and experts in the field to identify additional studies. SELECTION CRITERIA: We included randomised controlled, parallel trials of double versus single IUIs in stimulated cycles in subfertile couples. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data. We contacted study authors for additional information. MAIN RESULTS: We identified in nine studies involving subfertile women. The evidence was of low quality; the main limitations were unclear risk of bias, inconsistent results for some outcomes and imprecision, due to small trials with imprecise results. We are uncertain whether double IUI improves live birth rate compared to single IUI (odds ratio (OR) 1.15, 95% confidence interval (CI) 0.71 to 1.88; I2 = 29%; studies = 3, participants = 468; low quality evidence). The evidence suggests that if the chance of live birth following single IUI is 16%, the chance of live birth following double IUI would be between 12% and 27%. Performing a sensitivity analysis restricted to only randomised controlled trials (RCTs) with low risk of selection bias showed similar results. We are uncertain whether double IUI reduces miscarriage rate compared to single IUI (OR 1.78, 95% CI 0.98 to 3.24; I2 = 0%; studies = 6, participants = 2363; low quality evidence). The evidence suggests that chance of miscarriage following single IUI is 1.5% and the chance following double IUI would be between 1.5% and 5%. The reported clinical pregnancy rate per woman randomised may increase with double IUI group (OR 1.51, 95% CI 1.23 to 1.86; I2 = 34%; studies = 9, participants = 2716; low quality evidence). This result should be interpreted with caution due to the low quality of the evidence and the moderate inconsistency. The evidence suggests that the chance of a pregnancy following single IUI is 14% and the chance following double IUI would be between 16% and 23%. We are uncertain whether double IUI affects multiple pregnancy rate compared to single IUI (OR 2.04, 95% CI 0.91 to 4.56; I2 = 8%; studies = 5; participants = 2203; low quality evidence). The evidence suggests that chance of multiple pregnancy following single IUI is 0.7% and the chance following double IUI would be between 0.85% and 3.7%. We are uncertain whether double IUI has an effect on ectopic pregnancy rate compared to single IUI (OR 1.22, 95% CI 0.35 to 4.28; I2 = 0%; studies = 4, participants = 1048; low quality evidence). The evidence suggests that the chance of an ectopic pregnancy following single IUI is 0.8% and the chance following double IUI would be between 0.3% and 3.2%. AUTHORS' CONCLUSIONS: Our main analysis, of which the evidence is low quality, shows that we are uncertain if double IUI improves live birth and reduces miscarriage compared to single IUI. Our sensitivity analysis restricted to studies of low risk of selection bias for both outcomes is consistent with the main analysis. Clinical pregnancy rate may increase in the double IUI group, but this should be interpreted with caution due to the low quality evidence. We are uncertain whether double IUI has an effect on multiple pregnancy rate and ectopic pregnancy rate compared to single IUI