1. Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Thomas Jefferson University, Philadelphia, PA, USA;
2. BMJ-TAG, BMJ, London, UK;
3. Department of Neuroscience, Reproductive Science and Dentistry, School of Medicine, University of Naples “Federico II”, Naples, Italy;
4. Department of Obstetrics and Gynecology, Brighton and Sussex University Hospitals NHS Trust, Brighton, UK