Effects of Antenatal Betamethasone on Maternal and Fetoplacental Matrix Metalloproteinases 2 and 9 Activities in Human Singleton Pregnancies

Background A single course of antenatal betamethasone is administered to women at risk of preterm labor to advance fetal lung maturation. Matrix metalloproteinases (MMPs) are collagen-degrading enzymes that remodel extracellular matrix components during lung development. We tested the hypothesis that the effects of betamethasone on fetal lung maturation involve changes in MMP activity. Methods We conducted a prospective, observational pilot study of three groups of singleton pregnancies. Group 1 ( n = 21) was composed of women who were antenatally treated with a single course of betamethasone and who delivered n = 7) was composed of matched untreated women who delivered n = 15) was composed of untreated women who delivered > 37 weeks of gestation. Maternal blood, mixed cord blood, and placental samples were collected at the time of delivery for MMP-2 and MMP-9 activity and tissue inhibitor of metalloproteinases (TIMP)-1 and -2 levels. Results MMP-2 activity was significantly higher in the maternal, placental, and fetal compartments in group 1 compared with group 2 ( p p p p Conclusion We conclude that elevated MMP-2 activity in the maternal and fetoplacental compartments may suggest a mechanism, in part, for betamethasone-induced fetal lung maturation.