1. NaturalCycles Nordic AB, Stockholm, Sweden;
2. Department of Clinical Sciences at Danderyd Hospital, Karolinska Institutet, Stockholm, Sweden;
3. Department of Women’s and Children’s Health, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden;
4. Carl von Linné Clinic, Uppsala, Sweden;
5. Centre for Reproductive Biology in Uppsala, Uppsala, Sweden;
6. Office of Population Research, Princeton University, Princeton, NJ, USA