© 2020 American Society for Investigative Pathology Preterm premature rupture of membranes (PPROM) and thrombin generation by decidual cell–expressed tissue factor often accompany abruptions. Underlying mechanisms remain unclear. We hypothesized that thrombin-induced colony-stimulating factor-2 (CSF-2) in decidual cells triggers paracrine signaling via its receptor (CSF2R) in trophoblasts, promoting fetal membrane weakening and abruption-associated PPROM. Decidua basalis sections from term (n = 10), idiopathic preterm birth (PTB; n = 8), and abruption-complicated pregnancies (n = 8) were immunostained for CSF-2. Real-time quantitative PCR measured CSF2 and CSF2R mRNA levels. Term decidual cell (TDC) monolayers were treated with 10−8 mol/L estradiol ± 10−7 mol/L medroxyprogesterone acetate (MPA) ± 1 IU/mL thrombin pretreatment for 4 hours, washed, and then incubated in control medium with estradiol ± MPA. TDC-derived conditioned media supernatant effects on fetal membrane weakening were analyzed. Immunostaining localized CSF-2 primarily to decidual cell cytoplasm and cytotrophoblast cell membranes. CSF-2 immunoreactivity was higher in abruption-complicated or idiopathic PTB specimens versus normal term specimens (P < 0.001). CSF2 mRNA was higher in TDCs versus cytotrophoblasts (P < 0.05), whereas CSF2R mRNA was 1.3 × 104–fold higher in cytotrophoblasts versus TDCs (P < 0.001). Thrombin enhanced CSF-2 secretion in TDC cultures fourfold (P < 0.05); MPA reduced this effect. Thrombin-pretreated TDC-derived conditioned media supernatant weakened fetal membranes (P < 0.05), which MPA inhibited. TDC-derived CSF-2, acting via trophoblast-expressed CSFR2, contributes to thrombin-induced fetal membrane weakening, eliciting abruption-related PPROM and PTB.