Protocol of the PROMOTE study: characterization of the microbiome, the immune response, and one-carbon metabolism in preconceptional and pregnant women with and without obesity (an observational subcohort of the Rotterdam Periconception cohort) - Nicole Schenkelaars; Lieske Wekema; Marijke M. Faas; Régine P.M. Steegers-Theunissen; Sam Schoenmakers (PLoS ONE, 2025)