The objective of our study is to determine the clinical utility related to the maintenance oral nifedipine therapy in patients with symptomatic placenta previa. This study is a prospective, randomized controlled trial with the inclusion, after 24 weeks gestation, of hospitalized patients with symptomatic placenta praevia. All patients may initially receive oral nifedipine therapy with steroid prophylaxis for 48 hours. After then, patients are randomly assigned to receive either oral nifedipine (20 mg every 8 hours) or placebo (one every 8 hours) until 37 weeks of gestation.

The primary outcome for the trial is the length of pregnancy in days after the enrollment. A sample size calculation is designed to detect at least a 14 -day difference in time gained in patients with maintenance oral nifedipine therapy. A sample size of about 52 patients per group would have a 80 % chance of detecting this difference at the 5 % level of significance.

Inclusion Criteria:

• Placenta previa is diagnosed when the lowest placental edge is located within 5 cm of the internal os at ultrasonography
• Placenta previa may be symptomatic with at least one episode of bleeding
• Estimated gestational age within 24 to 34 weeks
• Maternal age > 18 years
• Informed consent after received an explanation of the study and an information sheet
• Social affiliation

Exclusion Criteria:

• Premature rupture of membranes
• Severe bleeding requiring an immediate termination of pregnancy
• Abnormal fetal heart rates requiring an immediate termination of pregnancy
• Intrauterine fetal death
• Pre-eclampsia, chorioamnionitis, liver disease, severe chronic renal disease, heart disease
• Abruptio placentae
• Nifedipine sensibility
• Drugs interaction with nifedipine