1. Copenhagen Prospective Studies on Asthma in Childhood (COPSAC), Herlev and Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark
2. Department of Pediatrics, Naestved Hospital, Naestved, Denmark; and
3. Department of Obstetrics and Gynecology, and
4. Department of Clinical Sciences, Skåne University Hospital, Lund University, Lund, Sweden