In order to evaluate whether dimerization of matrix metalloproteinases plays a role in hypertensive pregnancy (HTN-Preg) and intrauterine growth restriction (IUGR) Chen et al., 2017, measured the levels/activity of MMP-9, tissue inhibitor of metalloproteinase (TIMP-1), and their dimerization forms in the placenta, uterus, and uterine artery of normal pregnant rats and a rat model of RUPP. This evidence concerns the gene MMP9 and fetal growth restriction.