Least Square Means (LS Mean) of Chorion Thickness by Clinical Group and Membrane Collection Site.

Value shown is the least square mean of chorion thickness among all subjects within each of the five clinical groups compared with standard errors. P less than 0.01 by Poisson regression analysis. *Statistical comparison between PPROM and all other clinical groups (LS Mean). PPROM = Preterm, premature rupture of membranes (subjects between 24 and 34 weeks following confirmation of rupture of membranes by physical exam). Preterm Labor = subjects between 24 and 34 weeks of gestation with spontaneous preterm labor. Preterm, No Labor = subjects between 24 and 34 weeks of gestation delivered preterm without labor exposure. Term = subjects between 37 and 41 weeks with labor. Term, No Labor = subjects between 37 and 41 weeks without exposure to labor. Rupture = sample of membrane collected at site of rupture. Distant = sample of membrane collected from an area distant to rupture site, most commonly near the placenta.