Risk Factors Associated With Placenta Previa: A Matched Case-Control Study

Introduction Placenta praevia is a recognized pregnancy complication characterized by the placenta implanting partially or completely within the lower uterine segment, and it is associated with significant maternal and perinatal morbidity. Antepartum hemorrhage is a cardinal sign of placenta praevia, and it is unusual for a woman with placenta praevia to reach the late third trimester without vaginal bleeding. Many risk factors, i.e., age >30 years, previous caesarean section, history of dilatation and curettage, history of assisted reproductive techniques (ARTs), multiple pregnancies, and history of placenta praevia in previous pregnancies, need to be addressed so that a confirmed diagnosis can be made in the antenatal period, and women who are at increased risk for this condition can be managed or referred to a setup where proper and vigilant care is provided to both mother and baby. This study aims to identify the risk factors unique to our population and to stratify antenatal patients into high-risk and lower-risk pregnancy groups.  Methods The study was conducted in the Obstetrical Department of Ayub Teaching Hospital, Abbottabad, Pakistan, after approval of the topic and completion of all prerequisites, for a period of three months from July 1, 2025, to September 30, 2025. Women diagnosed with placenta praevia, including low-lying placenta praevia, through ultrasound examinations after 32 completed weeks of gestation were included in the case group. A total of 30 patients were included in the case group. Similarly, 60 women with normal placental localization were included in the control group (case:control ratio, 1:2). Detailed history was taken and recorded in a predefined proforma. For qualitative data, the Chi-square test was used, and a p-value of <0.05 was considered significant. Results In our study, several factors were associated with placenta previa. Women older than 30 years were more likely to develop placenta previa, with nearly four times higher odds compared to younger women (odds ratio (OR) 3.92, 95% confidence interval (CI): 1.55-9.93; p = 0.0064). A history of previous cesarean section also increased the risk, with cases showing six times higher odds than controls (OR: 6.00, 95% CI: 2.28-15.77; p = 0.00037). Similarly, women who had previously undergone dilatation and curettage had over five times higher odds of placenta previa (OR: 5.20, 95% CI: 1.97-13.70; p = 0.00095), and those who conceived through ARTs were nearly four times more likely to develop the condition (OR: 3.80, 95% CI: 1.49-9.67; p = 0.0037). Notably, a previous history of placenta previa was the strongest predictor of recurrence, with affected women facing markedly higher odds of developing the condition again (OR: 11.0, 95% CI: 3.23-37.42; p = 0.0001).  Conclusion Our study highlights several key risk factors for placenta previa, including advanced maternal age, previous cesarean section, history of dilatation and curettage, ARTs, and prior placenta previa. Identifying these factors early can help clinicians recognize women at higher risk and implement careful monitoring to prevent complications. While our findings align with larger studies, they provide additional insight by examining these associations within a focused case-control setting. Overall, these results emphasize the importance of individualized risk assessment and proactive management to improve maternal and fetal outcomes in pregnancies complicated by placenta previa.