A study of the relationship between placenta growth factor and gestationalage, parturition, rupture of membranes, and intrauterine infection

OBJECTIVE: Placenta growth factor is a potent angiogenic factor produced by the human placenta that has been implicated in the pathogenesis of preecla mpsia and intrauterine growth restriction. Placenta growth factor belongs t o the vascular endothelial growth factor family and is capable of inducing proliferation, migration, and activation of endothelial cells. The objectiv e of this study was to determine the relationship between amniotic fluid co ncentration of placenta growth factor and gestational age, parturition (ter m and preterm), spontaneous rupture of the membranes, and intra-amniotic in fection. STUDY DESIGN: Amniotic fluid samples obtained from 273 pregnant patients we re assayed in the following clinical groups: midtrimester pregnancy, preter m labor who delivered at term, preterm labor without microbial invasion of the amniotic cavity who delivered preterm, preterm labor with microbial inv asion of the amniotic cavity, term not in labor, term in labor, term with m icrobial invasion of the amniotic cavity, preterm premature rupture of memb ranes with and without microbial invasion of the amniotic cavity, and term with premature rupture of membranes without microbial invasion of the amnio tic cavity. The placenta growth factor concentrations were determined by an immunoassay that is both sensitive and specific. RESULTS: Placenta growth factor was detectable in 96.3% (263/273) of sample s. Amniotic fluid placenta growth factor concentration decreased with advan cing gestational age (r = -0.42; P < .001). Amniotic fluid placenta growth factor concentrations were significantly higher in women in midtrimester pr egnancy than in those at term not in labor (midtrimester pregnancy: median, 43.1 pg/mL; range, 22.9-69.8 pg/mL; vs term not in labor: median, 28.7 pg/ mL; range, 16.1-82.7 pg/mL; P < .01). Neither term nor preterm parturition was associated with a change in amniotic fluid placenta growth factor conce ntrations. Term premature rupture of membranes was associated with a signif icant decrease in amniotic fluid placenta growth factor concentration (term premature rupture of membranes: median, 16.5 pg/mL; range <5.2-195.1 pg/mL ; vs term intact membranes: median, 28.7 pg/mL; range, 16.1-822.7 pg/mL; P < .005). Preterm premature rupture of membranes was not associated with cha nges in amniotic fluid placenta growth factor concentrations. Intra-amnioti c infection in preterm labor, term labor with intact membranes, and preterm premature rupture of membranes were not associated with changes in amnioti c fluid placenta growth factor concentrations. CONCLUSION: Placenta growth factor is a physiologic constituent of amniotic fluid. Amniotic fluid concentrations of placenta growth factor decrease wi th advancing gestational age. Neither parturition nor infection affects amn iotic fluid placenta growth factor concentrations.