Myometrial Thickness as a Predictor for the Latency Interval in PPROM

100 women divided into 3 groups: * Group I: included 50 women with preterm premature rupture of membranes (PPROM, n=50) with gestational age from 24 to 34 weeks. * Group II: included 25 term non-labor control (T-CTR, n=25) with gestational age from 37 to 41 weeks. * Group III: included 25 preterm non-labor control (P-CTR, n=25) with gestational age from 24 to 34 weeks.The myometrial thickness at 4 different sites9: a) The lower uterine segment (LUS): 2cm above the reflection of the full urinary bladder (b)The anterior wall: 1cm above the maternal umbilicus. (c)Fundus: by placing the scan probe perpendicularly above the uterine fundus so that the entire curvature of the uterus was visualized. (d)The posterior wall: through using the maternal abdominal aortic pulsation as an anatomic marker. At least 3 measurements were obtained at each site and averaged. The latency interval is determined in each of the 3 groups.