Biased sampling of methane release from northern lakes: A problem for extrapolation

Methane emissions from lakes are widely thought to be highly irregular and difficult to quantify with anything other than numerous distributed measurement stations and long-term sampling campaigns. In spite of this, a large majority of the study sites north of 50 degrees N have been measured over surprisingly short time periods of only one to a few days. Using long-term data from three intensively studied small subarctic lakes, we recommend that measurements of diffusive methane flux and ebullition should be made over at least 11 and 39days scattered throughout the ice-free season using depth-stratified sampling at 3 and 11 or more locations, respectively. We further show that low temporal and spatial resolutions are unlikely to cause overestimates. Therefore, we argue that most sites measured previously are likely underestimated in terms of emission potential. Avoiding these biases seen in much of the contemporary data is crucial to further constrain large-scale methane emissions from northern lakes and ponds.Funding Agencies|Swedish Research Council [2007-4547]; Nordic Center of Excellence DEFROST under Nordic Top-Level Research Initiative</p

[In Press] Vaginal progesterone for prevention of preterm birth in asymptomatic high-risk women with a normal cervical length : a systematic review and meta-analysis

Objective: To determine whether vaginal progesterone reduces spontaneous preterm birth (sPTB) before 37 weeks in asymptomatic high-risk women with a singleton pregnancy and normal mid-gestation cervical length. Study design: Databases were searched (from inception to December 2020) with the search terms “progesterone” and “premature birth” or “preterm birth”. Studies were screened and included if they assessed vaginal progesterone compared to placebo in women with normal cervical length. Data were pooled and synthesized in a meta-analysis using a random effects model. Data sources: MEDLINE and Embase databases. Study synthesis: Following PRISMA screening guidelines, data from 1127 women across three studies were available for synthesis. All studies had low risk of bias and were of high quality. The primary outcome was sPTB <37 weeks, with secondary outcomes of sPTB <34 weeks. Vaginal progesterone did not significantly reduce sPTB before 37 weeks, or before 34 weeks with a relative risk (RR) of 0.76 (95% CI 0.37–1.55, p ¼ .45) and 0.51 (95% CI 0.12–2.13, p ¼ .35), respectively. Conclusions: Vaginal progesterone does not decrease the risk of sPTB in high-risk singleton pregnancies with a normal mid-gestation cervical length