['The proteoglycan decorin stabilizes collagen whereas biglycan and hyaluronan disrupt well-organized collagen. The aim was to determine the concentrations of these constituents in fetal membranes in relation to gestational age, preterm labour, PPROM and chorioamnionitis.', 'Preterm fetal membranes (24-34 weeks gestation) were obtained from elective caesarean deliveries (N = 4), from PPROM (N = 14), and from preterm labour (N = 14). Term fetal membranes from elective caesarean deliveries (N = 9) and spontaneous vaginal deliveries (N = 11) were used for comparison. Chorioamnionitis was assessed histologically. The proteoglycans were analysed using alcian blue precipitation, SDS-PAGE and immunostaining. Hyaluronan was estimated by a radioimmunoassay.', 'Preterm amniotic membranes with chorioamnionitis displayed a 8-fold decrease in hyaluronan concentration as well as a pronounced (88%) degradation of decorin and biglycan (p < 0.05). The amnion from preterm elective caesarean sections had higher decorin (3.2 vs. 1.7 μg/mg, p < 0.05) and lower biglycan (0.4 vs. 1.0 μg/mg, p < 0.05) concentrations as compared to similar term amnion (p < 0.05), whereas the hyaluronan concentrations were not associated with gestational age. Also the chorio-decidua from preterm caesarean sections had higher decorin concentrations (1.8 vs. 1.0 μg/mg, p < 0.05) whereas the biglycan concentration was unchanged. Labour (term as well as preterm) was characterized by increased hyaluronan and biglycan concentrations in the amnion (not statistically significant).'] Is chorioamniontis in preterm delivery associated with degradation of decorin and biglycan and depletion of hyaluronan in fetal membranes?