The classic presentation of placenta previa is painless, bright red vaginal bleeding that often stops spontaneously and then recurs with labor.
Vaginal bleeding is most likely to occur in the third trimester. In a study of 179 patients, 33.7% of patients had their first bleeding episode prior to 30 weeks, with 44.6% experiencing bleeding after 30 weeks. Of all the patients with confirmed placenta previa, only 21.7% did not bleed at any time during their pregnancy. 
Placenta previa often leads to preterm delivery, with 44% of pregnancies with placenta previa delivered before 37 weeks. 
Any pregnant woman beyond the first trimester who presents with vaginal bleeding requires a speculum examination followed by diagnostic ultrasonography, unless previous documentation confirms no placenta previa.
Because of the risk of provoking life-threatening hemorrhage, a digital examination of the vagina is absolutely contraindicated until placenta previa is excluded.
Findings in a woman with placental previa may include the following:
Soft and nontender uterus
Normal fetal heart tones (usually)
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