1. Coordination of Gynecological and Perinatal Endocrinology, National Institute of Perinatology, Ministry of Health, Mexico City, México
2. Peri and Postmenopause Clinic, National Institute of Perinatology, Ministry of Health, Mexico City, México
3. Postgraduate and Research Section, Higher School of Medicine, National Polytechnic Institute, Mexico City, México
4. Research Division, Hospital Juárez de México, Ministry of Health, Mexico City, Mexico
5. Central Laboratory, National Institute of Perinatology, Ministry of Health, Mexico City, México
6. Department of Immunobiochemistry, National Institute of Perinatology, Ministry of Health, México City, Mexico