Previous cesarean section and abortion as risk factors for developing placenta previa

Area of Science:

• Obstetrics and Gynecology
• Reproductive Health
• Maternal-Fetal Medicine

Background:

• Placenta previa is a pregnancy complication where the placenta partially or completely covers the cervix.
• Previous uterine surgeries and pregnancy terminations are suspected risk factors for placenta previa.

Purpose of the Study:

• To investigate the association between prior cesarean sections and abortions and the subsequent risk of placenta previa.
• To quantify the increased risk of placenta previa based on the number of previous cesarean sections and abortions.

Main Methods:

• Retrospective analysis of singleton deliveries at National University Hospital of Singapore (1993-1997).
• Identification of placenta previa cases through clinical or ultrasonographic diagnosis.
• Statistical analysis to determine risk association and odds ratios.

Main Results:

• 164 out of 16,169 deliveries (1.0%) were diagnosed with placenta previa.
• Women with placenta previa had a significantly higher incidence of previous cesarean sections (p < 0.001).
• The risk of placenta previa increased with the number of prior cesarean sections (2.2x for 1, 4.1x for 2, 22.4x for 3) and with two or more abortions (2.1x).

Conclusions:

• A strong association exists between previous cesarean sections and the risk of developing placenta previa.
• The risk of placenta previa escalates with an increasing number of prior cesarean sections.
• A higher frequency of abortions is also associated with an increased predisposition to placenta previa.