1. School of Public Health, University of California at Berkeley, Berkeley, California, USA
2. School of Public Health, University at Albany, Albany, New York, USA
3. Department of Laboratory Medicine, University of Milano-Bicocca, School of Medicine, Hospital of Desio, Desio-Milano, Italy
4. Department of Obstetrics and Gynecology, Mangiagalli Hospital, University of Milan, Milan, Italy
5. Department of Obstetrics and Gynecology, University of Wisconsin Medical School, Madison, Wisconsin, USA
6. Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA