GN 44028 Another study in China indicated that rs6929137 was an osteoporosis susceptibility SNP. To our knowledge, few research had been examined the relations between bone health and SNPs in the ESR2, while no possible relations in PGR gene previously.SNP rs1256120 in ESR2 was reported to be associated with Adolescent idiopathic scoliosis predisposition and curve severity. Another research detected a significant association of rs960070 in ESR2 with hip fractures in 700 elderly Chinese subjects. Unexpectedly, no evidence of association between AIs-related MS-AEs and SNPs in ESR2 and PGR was found in this study. Matrix metalloproteinases are proteolytic, zinc-dependent enzymes capable of degrading extracellular matrix components, including collagen. The human MMP family currently consists of 26 HFI 142 members and is classified according to substrate specificity into collagenases, gelatinases, stromelysines, matrilysins, membrane type-MMPs and other MMPs. More specifically, MMP-9, also known as gelatinase B, plays a role in the remodeling of collagenous ECM and cleaves collagen type IV, the major basement membrane component, collagen type V and elastin. MMP-3 or stromelysin-1 degrades a wide range of ECM proteins and participates in proMMP activation. Their activity is regulated by tissue inhibitors of metalloproteinases of which four have been identified.. Inhibition of MMP activity occurs in a 1:1 stoichiometric relationship. The balance between collagenolysis and its inhibition is critical during ECM remodeling. An imbalanced MMP:TIMP ratio has been involved in various medical conditions in humans including cancer, rheumatoid arthritis, osteoarthritis, endometriosis and vascular diseases. Human pregnancy is characterized by a steady remodeling of the collagenous ECM in order to adapt fetal membranes and cervix to uterine and fetal growth as gestation progresses. MMPs play also a crucial role in birth-related events, including cervical ripening and dilatation and membrane weakening and rupture. Some MMPs are constitutively expressed during gestation, while the production of others are induced by active labor. Aberrant ECM degradation by MMPs has been documented during pregnancy complications including preterm birth. Preterm birth, defined as a delivery before 37 completed weeks gestation, is a multifactorial syndrome in which intrauterine infection is one of the most important mechanisms involved. IUI trigger MMP production via inflammatory mediators. Activation of the MMP cascade causes ECM degradation, predisposing membrane rupture and cervix ripening. A number of studies have shown that IUI, spontaneous rupture of the membranes and parturition either term or preterm are associated with elevated MMP-9 concentrations in amniotic fluid, but few studies have investigated the involvement of MMP-3 in labor and parturition.