Definition Preterm Labor: Labor occurring prior to the completion of 37 weeks' of gestation (228 weeks), or 196-258 days from the last menstrual period (LMP)
Definition Placenta previa: Abnormal location- of the placenta over,orin close proximity to the internal os. Incidence: approximately 1 /250 pregnancy nulliparas: 1/1000~1/1500 pregnancy grandmultiparas: 1/20