Amniotic Fluid PROK1 Profiling and Its Association with Infectious Preterm Birth

Prokineticin 1 (PROK1), known as EG-VEGF, is a key regulator of pregnancy, playing a crucial role from implantation to birth. Our studies have shown that circulating concentrations of PROK1 are highest during the first trimester and are elevated in pregnancy complications such as spontaneous preterm birth (sPTB). Additionally, we found that PROK1 is largely expressed by fetal membranes, suggesting its presence in amniotic fluid (AF). Despite these findings, no study has yet investigated PROK1 concentrations in AF or characterized its profile in relation to sPTB. PROK1 levels were measured in two cohorts of AF samples collected from uncomplicated pregnancies and sPTB patients (n = 117), and two cohorts of maternal serum samples collected from uncomplicated pregnancies (n = 290). Our findings revealed that PROK1 concentrations were, i) significantly higher in AF compared to maternal serum; ii) stable across the second and third trimesters in AF; iii) not affected by the process of labor and delivery; iv) significantly elevated in sPTB cases compared to term laboring controls; and v) higher in sPTB cases with intra-amniotic infection compared to those without infection. This study provides the first comprehensive characterization of PROK1 levels in AF, highlighting its potential involvement in spontaneous preterm birth, with or without infection.