Placenta previa occurs in about one out of every 200 births. While the exact cause is not known, these are common risk factors for placenta previa:
- Those who have experienced a previous pregnancy
- Women who have had placenta previa previously
- Have an abnormally shaped uterus or scars on their uterus from previous surgery
- Are 35 years or older
- Are carrying more than one baby
- Smoke