1. Natural Cycles Nordic AB, Stockholm, Sweden
2. Department of Obstetrics and Gynaecology, UNC-Chapel Hill, NC, USA
3. Department of Women’s and Children’s Health, Division for Neonatology,Obstetrics and Gynecology and Reproductive Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden
4. Department of Clinical Sciences at Danderyd Hospital, Karolinska Institutet, Sweden and Department of Obstetrics and Gynecology, Danderyd Hospital, Stockholm, Sweden
5. Western University of Health Sciences, Pomona, CA, USA