The Nurses ’Health Studies are long term epidemiological studies conducted on women’s health. They are among the largest investigations into risk factors for major chronic diseases in women ever conducted. Marta Crous-Bou and co-workers have published a new and interesting finding from it. Greater adherence to Mediterranean diet was significantly associated with longer leukocyte telomere length, a marker of biological aging. These results further support the health benefits of adherence to Mediterranean diet.

Elsewhere, Stefan Johansson and co-workers investigate the associations between maternal overweight and obesity and infant mortality outcomes.  They performed a population based cohort study including 1 857 822 births in Sweden. They found that not only maternal obesity but also maternal overweight (BMI 25–29) is associated with increased infant mortality risk, and the risk increases with increasing BMI. The excess mortality seems to be explained by an increased mortality risk in term births, mostly due to birth asphyxia and other neonatal morbidities, and by an increased prevalence of preterm births.

And now to something completely different:

Pragmatic clinical trials are comparative effectiveness studies conducted in real world settings to answer questions relevant to patients, clinicians, and healthcare decision makers. A successful pragmatic clinical trial requires engagement and input from all levels of a healthcare system. Karin Johnson and co-workers summarise best practices for researchers and partners in healthcare systems to establish collaborative relationships, develop research questions, and implement sustainable pragmatic clinical trials in the research methods and reporting section of The BMJ.

Georg Roeggla is an associate editor for The BMJ.